COVID-19: Why the Omicron variant has scientists worried

Written by James Kingsland on December 7, 2021 — Fact checked by Alexandra Sanfins, Ph.D.

 

COVID-19: Why the Omicron variant has scientists worried

Scientists have detected cases of a new variant of SARS-CoV-2, which is the virus that causes COVID-19, in a number of countries. Omicron (B.1.1.529) has an unprecedentedly large number of mutations in the part of its genome that encodes a key section of its spike protein, which the virus uses to infect host cells. This suggests that Omicron may be able to evade some of the immune protection afforded by vaccines, many of which are based on the original spike protein, and past infections.

 

Travelers looking at a flight notice board displaying canceled flights at OR Tambo International Airport in Johannesburg, South Africa, on November 27, 2021. PHILL MAGAKOE/Getty Images

On November 16, 2021, there were 136 daily recorded cases of COVID-19 in South Africa. By November 25, 2021, that number had risen to over 1,200.

 

More than 80% of these cases were in the densely populated province of Gauteng, which includes Johannesburg and Pretoria.

 

Researchers estimated that the R-value, which is the average number of new cases caused by each infection, was 1.47 for South Africa as a whole.

 

If R is more than 1, an outbreak will grow exponentially. In Gauteng province, R was 1.93.

 

Scientists at the Centre for Epidemic Response and Innovation (CERI) in Stellenbosch, South Africa, believe that a new variant of the virus known as Omicron (B.1.1.529) is responsible for these worrying figures.

 

There have been three previous peaks of infection in South Africa during the course of the pandemic, with the third due to the Delta variant. The latest surge coincides with the first detection of Omicron by scientists.

 

Scientists have sequenced around 100 confirmed cases of Omicron infection in South Africa. Most of the cases have been in Gauteng.

 

The new variant is also present in Botswana, Hong Kong, Europe, Canada, Israel, Japan, the United States, and elsewhere.

 

News briefing from South Africa

“The main message today is that you have to know the enemy in order to fight,” said Prof. Tulio de Oliveira, Ph.D., the director of CERI, at a virtual news briefing on November 25, 2021.

 

He went on to say that the variant’s genome contains “a very unusual constellation of mutations.” Many of these are confirmed or predicted to either help the virus evade the immune system or increase its transmissibility.

 

He said that there are around 50 mutations across the entire genome of the virus and more than 30 in the part that codes for its spike. This is the protein that allows the virus to invade its host cells.

 

A particular part of the spike called the receptor-binding domain (RBD) binds to a receptor called ACE2Trusted Source in the membrane of human cells.

 

Prof. Oliveira said that there is an exceptionally large number of changes within the RBD of the new variant.

 

Antibodies that bind to the RBD can prevent the virus from infecting cells. So, the RBD is a crucial target for COVID-19 vaccines, which provoke the immune system to make antibodies against particular protein sequences.

 

The Beta variant has three mutations in the RBD part of its genome, and the Delta variant has two, said Prof. Oliveira. However, according to the European Centre for Disease Prevention and Control, Omicron has 15 mutations there.

 

The concern among scientists is that the changes due to the mutations may prevent antibodies, which are generated through vaccination or an encounter with an older variant of the virus during an infection, from neutralizing the virus.

 

Therapeutic antibodies

Dr. Richard Lessells, Ph.D., an infectious disease specialist based at the Africa Centre for Health and Population Studies, told the news briefing that Omicron’s genome has several mutations associated with resistance to neutralizing antibodies.

 

These include not only antibodies generated through vaccination or natural infection but also therapeutic monoclonal antibodies.

 

Dr. Lessells said that the Omicron genome also has a cluster of mutations associated with more efficient entry into host cells and enhanced transmissibility.

 

In addition, it has a mutation associated with resistance to the body’s first line of defense against newly encountered pathogens, known as the innate immune system.

 

“All these things are what gives us some concern that this variant might have not just enhanced transmissibility, to spread more efficiently, but might also be able to get around parts of the immune system and the protection that we have in our immune system,” he said.

 

However, he emphasized that the combined effect of the mutations was unknown. There is even a possibility that Omicron may cause more mild symptoms than previous variants.

 

“We will only know for real by doing the studies in the laboratory […]. [T]hat work is already ongoing,” he added.

 

“We can make some predictions about the impact of the mutations, but the full significance remains uncertain, and the vaccines remain the critical tool to protect us.”

 

– Prof. Tulio de Oliveira, Ph.D.

 

A variant of concern

On November 26, 2021, the World Health Organization (WHO)Trusted Source designated B.1.1.529 a variant of concern and gave it the name Omicron (the 15th letter of the Greek alphabet).

 

Over the next few days, several countries around the world imposed additional restrictions on travelers returning from southern African countries.

 

Dr. Daniel Griffin, Ph.D., a virologist at Columbia University in New York City, told Medical News Today that the number of changes in the Omicron variant is very high compared with previous variants of SARS-CoV-2.

 

He speculates that the new variant may have evolved in an unvaccinated individual with a compromised immune system. This would have given the virus an unusually long time to develop adaptations to the human immune system.

 

“It is really not surprising that this variant is now being described, as we continue to have so many parts of the world with low vaccination coverage, giving the virus millions of opportunities to replicate and select for more fit variants,” said Dr. Griffin.

 

“We currently have limited data on this virus, but we can look at some of the spike protein changes, and, based on what we know about this virus, it is very appropriate to be concerned about immune evasion and potentials for this variant to replace the Delta variant,” he added.

 

Over the next few weeks, he said, the critical questions for scientists to answer will be:

 

How well will the different vaccines work against this variant?

What will its impact be on rates of reinfection?

Has Omicron already spread widely?

What is the relative fitness of Omicron compared with the Delta variant?

 

Enhanced transmissibility

Sharon Peacock, the director of the COVID-19 Genomics UK Consortium and a professor of public health and microbiology at the University of Cambridge in the United Kingdom, told the Science Media Centre in London that several changes in Omicron are consistent with enhanced transmissibility.

 

“Mutations are also present that have been associated in other variants with immune evasion,” she explained.

 

“But the significance of many of the mutations detected, and the combination of these mutations, is not known.”

 

She emphasized that there are currently no data on how much protection the current vaccines will provide against Omicron.

 

However, a recent small-scale study, which is yet to be peer-reviewed, adds some new information about vaccine effectiveness.

 

A series of small experiments with the Pfizer-BioNTech COVID-19 vaccine has found a drop in protection against the new Omicron variant.

 

The researchers compared the immune responses of six people who had received the vaccine and six who first developed COVID-19 before receiving the vaccination.

 

They found that, overall, there was a 41-fold reduction in neutralization against Omicron. However, five of the participants, all of whom had developed COVID-19, maintained “relatively high neutralization [levels] with Omicron.”

 

The study suggests that people who have had COVID-19 before this vaccine are likely to be better protected. The researchers expect this to be similar for people who have received a booster dose.

 

Although the findings are worrisome to an extent, scientists point out that looking solely at antibodies paints an incomplete picture of the body’s immune response to SARS-CoV-2, the virus that causes COVID-19 — especially against hospitalization or death.

 

However, as Prof. Peacock concludes, “In the meantime, vaccination should continue to proceed at pace.”

 

Public HealthInfectious Diseases / Bacteria / VirusesCOVID-19

Written by James Kingsland on December 7, 2021 — Fact checked by Alexandra Sanfins, Ph.D.

 

Are COVID-19 vaccine boosters the way forward?

There are growing concerns that COVID-19 vaccines do not offer sufficient protection against new variants of the SARS-CoV-2 virus. Israel has already started to offer booster shots of the Pfizer vaccine to at-risk adults, and the United States is in talks with Pfizer about introducing these shots for the most vulnerable.

 

There has been talk of a third dose for some COVID-19 vaccines. Why might vaccine boosters be necessary, and what are the questions researchers are yet to answer about them? Image credit: Jens Schlueter/Getty Images

There is growing evidence that people who have received COVID-19 vaccines are less likely to become infected with the virus that causes this disease and that if they do, they are less likely to have symptoms of severe illness.

 

However, evidence is also emerging that existing vaccines may offer less protection against new variants of SARS-CoV-2, such as the delta variant.

 

One studyTrusted Source, for example, showed that 95% of people who received both doses of the Pfizer-BioNTech or Oxford-AstraZeneca COVID-19 vaccine had a weaker immune response to the delta variant than to previous strains.

 

People who received just one dose of either vaccine had a very weak immune response, which suggests that a single dose of one of these vaccines does not offer adequate protection.

 

The Health Ministry of Israel also released a statement saying that the effectiveness of the Pfizer-BioNTech vaccine in preventing symptomatic COVID-19 fell to just 64% at 6 months post-vaccination. It noted, however, that two doses of Pfizer are still able to prevent serious illness in 93% of cases.

 

As of yet, the U.S. has made no decision as to whether they will approve access to booster vaccines. However, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) said in a joint statement that they are “prepared for booster doses if and when the science demonstrates that they are needed.”

 

What are vaccine boosters? 

Vaccine boosters are additional vaccine doses that should provide extra protection against disease, as the effects of some vaccines may wear off over time.

 

Vaccine boosters are common for many viral infections, including the flu, which requires a boless, booster doses might benefit older individuals or those wiology at Columbia Mailman School of Public Health, further explained that “[b]ooster shots might be most beneficial for those who have medical conditions — such as some solid organ transplant recipients (e.g., kidney transplant) and some individuals with autoimmune diseases (e.g., lupus) — that prevent them from developing an effective immune response after the first round of vaccination.”

 

However, she added, “[w]e would first need evidence that a booster shot for these individuals is safe and effective.”

 

Other scientists say that the opportunity cost of not providing booster vaccines outweighs the lack of research underpinning their use.

 

In an interview with the BMJTrusted Source, Prof. Anthony Harnden of the Joint Committee on Vaccination and Immunisation in the U.K. expressed the opinion that the U.K. is likely to roll out booster vaccines and that annual boosters might be necessary for some time.

 

Controversies around vaccine boosters

“Scientifically, there is nothing controversial about additional booster vaccinations; they work in very much the same way as a second vaccine in a two-vaccine schedule,” the Oxford COVID-19 Vaccine Team spokesperson told MNT.

 

“The debate around additional vaccines is whether they are needed at this stage or [whether] vaccine doses are better off being used elsewhere — particularly in poorer countries, as highlighted recently by Sir Andrew Pollard in an article in The Times newspaper,” they added.

 

Sir Andrew Pollard, director of the Oxford Vaccine Group at the University of Oxford, wrote that the main purpose of vaccines is to “keep people out of hospital.”

 

As vaccines seem to reduce hospitalizationsTrusted Source with COVID-19 significantly, and experts predict that vaccine supplies will be limited for the foreseeable future, Sir Andrew argues that it is important to prioritize those who have not yet had even a single shot before providing boosters to others.

 

Some people even question whether it is morally right to give booster shots to those who have already been vaccinated when many people, especially those in developing countries, have not received even one shot and are thus at a higher risk of infection.

 

Others question the need for a third vaccine.

 

In response to vaccination, T cells and B cells, which are part of the body’s immune system, react by building up long lasting immunity to the virus. B cells are the immune system’s “memory cells,” and they produce antibodies that bind to the virus. T cells help B cells produce these antibodies. Some T cells also kill infected cells.

ith a weak immune system, as their bodies may not have generated a strong enough immune response after the initial vaccines.“If that boost can be done with a vaccine that matches the newer strains, that will be even better — but that’s difficult because the virus is constantly changing, and it takes time to generate the vaccine, so we’re always playing catch-up. A boost with the older vaccine is still OK though — they do work against the new variants to prevent serious disease, especially if the immune response is strong,” he also noted.

 

Dr. Jessica Justman, associate professor of medicine in epidem

So far, one study — which has not yet undergone peer review but appears on an online preprint service — has suggested that people who have recovered from mild COVID-19 experience a lasting T-cell response.

 

“Based on current data, for people who respond well to the vaccine, it looks like immunity remains strong for over 12 months and works even against the new variants,” Dr. Richard Stanton, a reader in the Division of Infection and Immunity at Cardiff University in the United Kingdom, told MNT.

 

“My personal opinion is, therefore, that we don’t need to be too worried about boosting them yet,” he said.

 

However, he cautioned:

 

“Where we do need to be careful is in people who don’t respond well to the vaccine. There are lots of vulnerable groups in society who fall into this category, and we know from other vaccines that older people sometimes don’t have the same length of immunity as younger people. I think we should be looking carefully at whether it’s appropriate to give them a boost.”

 

Another study that features on a preprint service ahead of peer review found that, in people recovering from symptomatic or mild COVID-19, B cells can produce new antibodies that specifically target new variants of SARS-CoV-2.

 

The same lasting immune response is likelyTrusted Source to occur following a COVID-19 vaccine, some experts argue.

 

Research on COVID-19 vaccine boosters

Research investigating vaccine booster doses is currently underway. Some early studiesTrusted Source, however, suggest that although current vaccines offer some protection against existing variants, this may decrease as the virus mutates and new variants emerge.

 

For example, one study — shared online in preprint form — found that people fully immunized with the Pfizer-BioNTech or Oxford-AstraZeneca vaccines had a weaker antibody response upon exposure to the delta and beta variants of SARS-CoV-2, which scientists first identified in India and South Africa, respectively. This, say the

 researchers, means that booster vaccines based on updated variants may be necessary over time to prevent infections.

 

Another study — which also appears online via a preprint service — found that after receiving the one recommended dose of the Johnson & Johnson vaccine, people showed immunity against multiple SARS-CoV-2 variants, including the delta variant.

 

The researchers noted, however, that the immune response to the delta variant appeared to be weaker than that to previous variants of SARS-CoV-2.

 

, whether booster vaccine doses are truly helpful in the fight against COVID-19 remains an open question. For now, experts recommend taking a full course of whatever COVID-19 vaccine is available in a person’s country.

 

“We have learned a great deal about COVID vaccines in a very short time, but there’s still plenty we don’t know yet,” Dr. Justman told MNT.

 

Some of the questions that remain unanswered, she noted, include:

 

“Is it better to boost with the same vaccine (a homologous boost) that was initially given or with a different vaccine (a heterologous boost)?

What is the best method to measure the different components of the immune response after vaccination?

For those who take immunosuppressive medications, would a brief reduction in these medications be better than or just as good as a booster?

What dose should a booster be, and at what time interval?

Is a booster safe in all age groups?

[Are there] any groups who may not do well with a booster?

What age group would benefit most from a booster?”

These are all questions that researchers are doing their best to address as soon as possible. This does not change the fact, said Dr. Justman, that: “[t]he most important booster is to vaccinate as many people as possible right now, both here in the U.S. and globally.”

 

Can you 'detox' from the COVID-19 vaccine?

Increasing numbers of people are searching for information on how to “detox” themselves from the COVID-19 vaccine after receiving it, over fears it could have detrimental effects. But is this ever safe or even possible?

 

Can you really ‘detox the vaccine,’ and is it safe to try? Image credit: Ben Hasty/MediaNews Group/Reading Eagle via Getty Images

Nearly 3 out of 4 people in the United States have received a vaccination against COVID-19. Over 9 out of 10 of those who said they intended to get vaccinated in early 2021 have taken at least one dose.

 

Concerns raisedTrusted Source in the early summer about the low number of people receiving a vaccination against COVID-19 were relieved in August 2021 when the White House claimed a 70% increase in the daily average of first dose vaccinations compared to the previous month. Much of this uptake took place in areas that had previously had the lowest vaccination rates.

 

While the White House pointed to the increase in vaccine mandates for the boost in uptake, the September results from KFF COVID-19 Vaccine Monitor, a study about attitudes toward COVID-19 vaccines, considered the fear over the Delta variant to be behind the demand for the vaccine.

 

Whatever the motivation, the White House has continued to press ahead with increased mandates for vaccination in many settings.

 

Although the policies from the Biden Administration have experienced some setbacks, many businesses across the U.S. have already implemented them. About 1 in 4 workers say their employer required them to have a COVID-19 vaccination in October 2021, which, according to the KFF COVID-19 Vaccine Monitor, is an increase of 16% since June.

 

Against this political backdrop, the Food and Drug Administration (FDA) authorized vaccination for children aged 5-11Trusted Source in October and booster shots for all adultsTrusted Source in November.

 

This means that many people who may previously have been vaccine-hesitant have faced additional pressures to receive the vaccine.

 

The KFF COVID-19 Vaccine Monitor revealed that while 7 in 10 unvaccinated workers said they would leave their job if their employer asked them to get vaccinated, just 1 in 20 unvaccinated workers say they have actually done so,

 

“More than a third (37%) of unvaccinated workers (5% of adults overall) say they would leave their job if their employer required them to get a vaccine or get tested weekly, a share that rises to 7 in 10 unvaccinated workers (9% of all adults) if weekly testing is not an option,” their report also found.

 

Although vaccination rates might be slowing down, vaccination continues. This suggests that some people who are getting vaccines may not have planned on doing so previously.

 

Vaccinated but still hesitant

One peculiar phenomenon that has developed out of this recent landscape is that some people have started looking for information on how to “detox” from the vaccine after they have received it, particularly if they had not wanted to have it in the first place.

 

A TikTok video featuring claims that people who had had the COVID-19 vaccine should take complex “detox” baths, containing, among other things, borax, hit the headlines in November. However, that video was not the only example of emerging claims that people should detox from the vaccine to avoid unwanted side effects.

 

Suggestions for “detoxes” after receiving a COVID-19 vaccine ranged from borax baths to detox diets. Suggested detox diets included high fat diets to “bind the toxins” in the vaccines, alongside supplements, including zinc and vitamins C and D.

 

According to some media reports, some even suggested cupping the site of the injection to remove the vaccine.

 

More extreme claims suggest that people who have had the vaccine need to take a prophylactic dose of ivermectin and hydroxychloroquine to counteract what they believe to be a negative impact of the vaccine on their immune system. The FDA does not authorize the use of ivermectinTrusted Source or hydroxychloroquineTrusted Source to combat COVID-19 but rather advises against using ivermectin for this purpose.

 

While the rise of this misinformation may seem baffling to some, Prof. Monica Gandhi, professor of medicine at the University of California San Francisco and an HIV doctor, feels that social media is partly to blame.

 

Speaking to Medical News Today, she pointed to the fact that there was always misinformation about HIV from high profile academics, and at one point, the President of South Africa, “but it didn’t end up having this reach that you can have when you have social media platforms, with people with MD and Ph.D. after their names who are allowed to put out there that mRNA and proteins stay around in your body, that it is toxic and that it kills other cells.”

 

She added that while there is a lot of anger in the U.S. towards people who are not vaccinated, she just feels sadness about the situation:

 

“If you’re very worried about these vaccines, if you’ve been convinced by someone who has an MD after their name that they’re dangerous, then you’ll do everything in your power, especially if there’s a mandate, to detox or to get that protein or the mRNA out of your body. I mean, you’re really, really worried. That is what misinformation does; it truly worries you.”

 

Vaccine mandates for children and schools

People keen to promote the message that vaccines can be harmful, whether it is around false claims that the MMR can cause autismTrusted Source or that heavy metals used as preservatives in them are toxic to children, have targeted parents and caregivers.

 

Now, over half of the parents in the U.S. said they worry that their child may be required to get vaccinated for COVID-19 even if they do not want them to, the Vaccine Monitor reported in October.

 

In California, where vaccine mandates are expected to come into full force in July 2022, reports indicate that parents are pressurizing doctors to invoke inappropriate medical exemptions, homeschooling, and moving away from the state.

 

Dr. David Shafran, head of pediatrics at K Health in Cleveland, OH, has not had any parents come to see him asking how to “detox” their children after receiving the COVID-19 vaccine. He told MNT in an email:

 

“While I advocate for the COVID vaccine, I can understand and have seen the uneasiness that mandates can elicit when folks feel pushed into an intervention before they’ve wrapped their minds fully around it, especially when it comes to their children.”

 

“Perhaps vaccinating before full readiness results in the compulsion to somehow mitigate the ‘unwanted’ intervention. But I would like to reassure parents that the immune response from the vaccine is a protective one that cannot be reversed or undone, so please avoid unproven and potentially harmful interventions.”

 

Are mRNA vaccines harmful?

Much of the concern seems to center on the suggestion that mRNA vaccines are potentially harmful, and the fact that they are a new drug means that we do not fully understand their impact yet. But there is little evidence to suggest that they can be harmful, scientists say.

 

It was worth noting that the mRNA vaccines that have been developed actually use a modified form of mRNA to reduce the risk of unwanted side effects, says professor of Immunology at the University of Bern in Switzerland, Prof. Martin Bachmann.

 

In an interview, he explained to MNT that: “These are not normal RNA molecules; they’re slightly modified. And the more you modify them, I guess the less toxic they will be, but then they may also be less effective at actually immunizing, so I’m sure [pharmaceutical companies] found some compromise there between safety and the efficacy.”

 

“If the body doesn’t recognize it, then it won’t be toxic,” he pointed out. “So if you’ve modified your RNA and the body does not recognize the mRNA, you’re more likely to have essentially no side effects except the very rare ones. But if you completely modify the RNA, you probably won’t have an effective vaccine.”

 

Dr. Shafran concurred, saying that the COVID-19 vaccine “is irrevocable and that’s not a bad thing.”

 

He also explained:

 

“The mRNA vaccines induce an immune response in the form of antibodies targeting specifically the spike protein of the SARS-CoV-2 virus that protects strongly against infection. Once these antibodies have formed, there’s no going back; the immune system is primed to fight COVID always and forever. We know these antibodies circulate for at least 6–12 months, with longer immunity likely conferred as well, even after ‘visible’ antibody counts decline.”

 

Are heavy metals in vaccines ‘toxic’?

Claims that heavy metals in vaccines are “toxic” is a claim that people who oppose vaccine use have been making since long before the development of the COVID-19 vaccines.

 

This is likely due to the fact that heavy metals have been ingredients in vaccines for decades, often as an adjuvantTrusted Source or present in preservativesTrusted Source. While there are historical concernsTrusted Source raised by the FDATrusted Source over the use of thimerosal, a molecule containing mercury, in vaccines for children, research into this has shown that there are no health risks. People have been routinely receiving vaccines containing these ingredients for decades.

 

According to a fact check by Reuters, thimerosal is not an ingredient in COVID-19 vaccines.

 

“Heavy metals, of course, are toxic, but that is dependent on the dose. But, this is not a dose [in vaccines] that could be dangerous. Everything is dose-dependent. Water is bad for you if you drown in a lake!” said Prof. Bachmann.

 

The amount that is in the vaccine is not dangerous, but COVID-19 is, he emphasized.

 

As Professor Gandhi points out, you only need to look at the scale of vaccines that have been delivered to realize they are safe.

 

“7.4 billion doses have been administered now worldwide, of different vaccines with COVID, and a lot of those are mRNA vaccines. So you know, if there were a lot of adverse events, we would have seen a lot of damage. But we don’t see that,” she pointed out.oster every year, and tetanus, diphtheria, and pertussis (DTaP), for which a booster is necessary every 10 years.

 

For some vaccines, receiving smaller doses more often is more effective than getting a single large vaccine dose.

 

This approach allows the immune system to build its immune response sustainably. When the immune system remembers certain antigens that previously activated it, it can respond much quicker the next time it encounters them.

 

Although many vaccine boosters are identical to the previous doses, some are modified to enhance their efficacy. The flu vaccine, for example, changes every year to respond more effectively to new mutations of the influenza virus.

 

Why take booster doses? 

There are generally two reasons why people might consider vaccine boosters. The first is that immunity naturally wanes over time. Without repeated exposure to certain antigens, the immune system may become less able to prevent infection or disease. Vaccine boosters help the immune system maintain a protective response.

 

“Another reason we may need booster vaccinations is viral variants,” a spokesperson from the COVID-19 Vaccine Team at the University of Oxford told Medical News Today. They went on to explain:

 

“Some variants have evolved to avoid some parts of our immune response, which means they can more easily infect those who have an existing immune response to the virus — i.e., those who have been previously infected or vaccinated. However, the virus cannot avoid all parts of our immune response. A booster vaccination is helpful, as it can improve the parts of our immune response the viral variant cannot avoid.”

 

“Alternatively, we can use a booster vaccine that specifically targets the viral variant. This works by producing a new immune response to the parts of the virus which have changed from the original vaccine whilst also improving the existing immune response against the unchanged parts of the virus, which also should help protect against other variants,” they added.

 

However, it remains unclear for how long COVID-19 vaccines — in the current dosages — continue to offer protection.

Nevertheless, booster doses might benefit older individuals or those with a weak immune system, as their bodies may not have generated a strong enough immune response after the initial vaccines.

“Based on current data, for people who respond well to the vaccine, it looks like immunity remains strong for over 12 months and works even against the new variants,” Dr. Richard Stanton, a reader in the Division of Infection and Immunity at Cardiff University in the United Kingdom, told MNT.

“My personal opinion is, therefore, that we don’t need to be too worried about boosting them yet,” he said.

However, he cautioned: “Where we do need to be careful is in people who don’t respond well to the vaccine. There are lots of vulnerable groups in society who fall into this category, and we know from other vaccines that older people sometimes don’t have the same length of immunity as younger people. I think we should be looking carefully at whether it’s appropriate to give them a boost.”

“If that boost can be done with a vaccine that matches the newer strains, that will be even better — but that’s difficult because the virus is constantly changing, and it takes time to generate the vaccine, so we’re always playing catch-up. A boost with the older vaccine is still OK though — they do work against the new variants to prevent serious disease, especially if the immune response is strong,” he also noted.

Dr. Jessica Justman, associate professor of medicine in epidemiology at Columbia Mailman School of Public Health, further explained that “[b]ooster shots might be most beneficial for those who have medical conditions — such as some solid organ transplant recipients (e.g., kidney transplant) and some individuals with autoimmune diseases (e.g., lupus) — that prevent them from developing an effective immune response after the first round of vaccination.”

However, she added, “[w]e would first need evidence that a booster shot for these individuals is safe and effective.”

Other scientists say that the opportunity cost of not providing booster vaccines outweighs the lack of research underpinning their use.

In an interview with the BMJ, Prof. Anthony Harnden of the Joint Committee on Vaccination and Immunisation in the U.K. expressed the opinion that the U.K. is likely to roll out booster vaccines and that annual boosters might be necessary for some time.

Controversies around vaccine boosters

“Scientifically, there is nothing controversial about additional booster vaccinations; they work in very much the same way as a second vaccine in a two-vaccine schedule,” the Oxford COVID-19 Vaccine Team spokesperson told MNT.

“The debate around additional vaccines is whether they are needed at this stage or [whether] vaccine doses are better off being used elsewhere — particularly in poorer countries, as highlighted recently by Sir Andrew Pollard in an article in The Times newspaper,” they added.

Sir Andrew Pollard, director of the Oxford Vaccine Group at the University of Oxford, wrote that the main purpose of vaccines is to “keep people out of hospital.”

As vaccines seem to reduce hospitalizations with COVID-19 significantly, and experts predict that vaccine supplies will be limited for the foreseeable future, Sir Andrew argues that it is important to prioritize those who have not yet had even a single shot before providing boosters to others.

Some people even question whether it is morally right to give booster shots to those who have already been vaccinated when many people, especially those in developing countries, have not received even one shot and are thus at a higher risk of infection.

Others question the need for a third vaccine.

In response to vaccination, T cells and B cells, which are part of the body’s immune system, react by building up long lasting immunity to the virus. B cells are the immune system’s “memory cells,” and they produce antibodies that bind to the virus. T cells help B cells produce these antibodies. Some T cells also kill infected cells.

So far, one study — which has not yet undergone peer review but appears on an online preprint service — has suggested that people who have recovered from mild COVID-19 experience a lasting T-cell response.

Another study that features on a preprint service ahead of peer review found that, in people recovering from symptomatic or mild COVID-19, B cells can produce new antibodies that specifically target new variants of SARS-CoV-2.

The same lasting immune response is likely to occur following a COVID-19 vaccine, some experts argue.

Research on COVID-19 vaccine boosters

Research investigating vaccine booster doses is currently underway. Some early studies, however, suggest that although current vaccines offer some protection against existing variants, this may decrease as the virus mutates and new variants emerge.

For example, one study — shared online in preprint form — found that people fully immunized with the Pfizer-BioNTech or Oxford-AstraZeneca vaccines had a weaker antibody response upon exposure to the delta and beta variants of SARS-CoV-2, which scientists first identified in India and South Africa, respectively. This, say the researchers, means that booster vaccines based on updated variants may be necessary over time to prevent infections.

Another study — which also appears online via a preprint service — found that after receiving the one recommended dose of the Johnson & Johnson vaccine, people showed immunity against multiple SARS-CoV-2 variants, including the delta variant.

The researchers noted, however, that the immune response to the delta variant appeared to be weaker than that to previous variants of SARS-CoV-2.

On July 8, 2021, Pfizer and BioNTech released a statement saying that giving booster doses of their vaccine 6 months after the second dose produces an immune response to several variants of the virus that is 5–10 times more potent than that following the second dose. They state, however, that they are creating an updated version of the vaccine to target the delta variant.

Many clinical trials are underway to learn more about the duration of immunity in regular vaccine regimens, how it changes after a third dose, and what happens if that third dose is a better match for new variants. As most of these trials have just begun, results will not be available for some time, though.

For example, the National Institutes of Health (NIH) launched a trial  in June 2021 to determine the safety and effectiveness of a third vaccine dose from a different brand. Researchers will follow the participants for a year after their third vaccination, meaning that the results of this study will emerge by mid-2022 at the earliest.

The results of this trial will inform public policy decisions on whether booster shots are necessary to keep up with the virus as new variants emerge. Similar trials are also underway at the University of Washington and the University of Southampton in the U.K.

Until scientists collect and publish the results from these studies, whether booster vaccine doses are truly helpful in the fight against COVID-19 remains an open question. For now, experts recommend taking a full course of whatever COVID-19 vaccine is available in a person’s country.

“We have learned a great deal about COVID vaccines in a very short time, but there’s still plenty we don’t know yet,” Dr. Justman told MNT.

Some of the questions that remain unanswered, she noted, include:

• “Is it better to boost with the same vaccine (a homologous boost) that was initially given or with a different vaccine (a heterologous boost)?

• What is the best method to measure the different components of the immune response after vaccination?

• For those who take immunosuppressive medications, would a brief reduction in these medications be better than or just as good as a booster?

• What dose should a booster be, and at what time interval?

• Is a booster safe in all age groups?

• [Are there] any groups who may not do well with a booster?

• What age group would benefit most from a booster?”

These are all questions that researchers are doing their best to address as soon as possible. This does not change the fact, said Dr. Justman, that: “[t]he most important booster is to vaccinate as many people as possible right now, both here in the U.S. and globally.”

 

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