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COVID-19 vaccines are critical for controlling the pandemic; vaccines still offer partial protection against new variants of the virus

Posted on:  2021-03-23

Key takeaway

Emerging variants of the virus that causes COVID-19, some of which are more transmissible, have led to speculation about the efficacy of current COVID-19 vaccines. Emerging variants are subject to continuous monitoring to evaluate their potential impact on COVID-19 transmission and disease outcomes. The evidence so far indicates that COVID-19 vaccines still confer partial protection against these variants. Furthermore, the COVID-19 vaccines in use can be rapidly modified, and manufacturers are already anticipating new vaccine formulations to improve their efficacy against the new variants.

Reviewed content


COVID-19 mass vaccination will select for more virulent variants of the virus that causes COVID-19, which will escape vaccine-induced immunity and cause more severe disease

Source: Children's Health Defense, The Highwire, Geert Vanden Bossche, 2021-03-06

Verdict detail

Inadequate support: No evidence indicates that vaccination will lead to more virulent variants of the virus that causes COVID-19. The claims that vaccination will select for viral variants that can escape vaccine-induced immunity and cause more severe disease than those that evolve naturally in unvaccinated populations are unsupported.
Lacks context: Preliminary data suggest that COVID-19 vaccines very likely reduce viral transmission to some degree, contrary to Vanden Bosschen’s claim. COVID-19 vaccines are highly effective at preventing disease and also confer partial protection against variants of the virus. Furthermore, COVID-19 vaccines can be reformulated if needed to match new variants.
Incorrect: Vaccines stimulate the humoral immune response without weakening innate immunity. Immunization may even enhance natural antibody response.

Full Claim

“all these kinds of highly infectious variants, it's very clear, that this is driving immune escape and will ultimately drive resistance to the vaccines”; “prophylactic vaccines should typically not be administered to people who are exposed to high infectious pressure”; “when we vaccinate somebody we are turning this person into a potential asymptomatic carrier that is shedding the virus”; “these long-lived antibodies, which have high specificity of course for the virus, they out-compete our natural antibodies”


On 6 March 2021, Geert Vanden Bossche, an independent consultant who previously worked in vaccine development, published an open letter to the World Health Organization on Twitter. In it, Vanden Bossche claimed that COVID-19 vaccines “should not be used amid an epidemic” and called for a halt to mass vaccination campaigns. The same day, a video interview with Vanden Bossche was published on YouTube. Vanden Bosche’s tweet was retweeted more than 6,000 times and received more than 6,700 likes. The video received more than 67,000 interactions on social media platforms, including Facebook and Reddit.

The video interview was further disseminated on platforms like Bitchute and organizations opposing vaccination, such as Children’s Health Defense. It was also commented on by Del Bigtree, founder of the anti-vaccination group Informed Consent Action Network. All of these platforms published misinformation about COVID-19 and vaccines in the past.

Vanden Bossche claimed that global COVID-19 vaccination campaigns would accelerate the emergence of dangerous variants, which will escape vaccine-induced immunity and cause severe disease. However, this claim is based on several flawed and unsupported assumptions that invalidate Vanden Bossche’s conclusions, as we explain below.

Preliminary evidence indicates that COVID-19 vaccines likely reduce transmission to some degree

Claim (Unsupported): “when we vaccinate somebody, we are turning this person into a potential asymptomatic carrier that is shedding the virus”

Vanden Bossche’s claim is based on two assumptions. The first is that COVID-19 vaccines “don’t prevent infection, they protect against disease”. The second is that vaccination doesn’t reduce transmission. These assumptions are unsupported, as Health Feedback previously explained in this review.

COVID-19 vaccine trials evaluated the vaccine’s efficacy in preventing disease, but most of them weren’t designed to detect whether the vaccine prevented infection. As a result, there is insufficient data to determine whether COVID-19 vaccines completely block transmission by preventing infection in vaccinated individuals altogether or reduce the likelihood of transmission by reducing the amount of virus produced by a vaccinated person who becomes infected. However, preliminary evidence indicates that COVID-19 vaccines very likely reduce viral transmission, at least to some degree.

Interim results from the Moderna and Johnson & Johnson COVID-19 vaccine trials showed fewer asymptomatic infections among vaccinated individuals. In Israel, one preprint, which is a study that has not yet been peer-reviewed, reported that infected individuals who received one dose of the Pfizer-BioNTech vaccine had viral loads that were four times less than those of unvaccinated individuals[1].

It remains unclear whether this reduction in viral load is enough to significantly reduce contagiousness in the real world. Nevertheless, the results indicate that COVID-19 vaccines have the potential to limit COVID-19 transmission by reducing the contagiousness of vaccinated individuals who become infected, even if they don’t prevent a vaccinated person from becoming infected altogether.

Preliminary data from countries with high vaccination rates, such as Israel, the U.K., and the U.S., suggest that COVID-19 vaccines reduce viral transmission in the real world. One study published in The New England Journal of Medicine found that there were 92% fewer infections among individuals in Israel who received both doses of the Pfizer-BioNTech vaccine compared to unvaccinated individuals[2].

In the U.S., another study showed 80% fewer asymptomatic infections among people who received at least one dose of the Pfizer-BioNTech or Moderna COVID-19 vaccine compared to unvaccinated individuals[3].

In March 2021, researchers in the U.K. published a preprint showing that the risk of COVID-19 infection was 30% lower in household members of healthcare workers who received at least one dose of the Pfizer-BioNTech or Oxford-AstraZeneca vaccine than in household members of unvaccinated workers[4].

Combined, the evidence above suggests that COVID-19 vaccines very likely reduce viral transmission, contrary to what Vanden Bossche claimed.

No evidence indicates that COVID-19 vaccines will lead to more variants than natural evolution, and emerging variants aren’t necessarily more virulent

Claim (Lacks context): “prophylactic vaccines should typically not be administered to people who are exposed to high infectious pressure”

A virus can produce mutations, or changes in its genetic sequence, each time it replicates during the infection process. The more infections the virus causes, the more times it replicates, increasing the likelihood of generating new mutations.

Vanden Bossche claimed that vaccines shouldn’t be administered during an epidemic because mass COVID-19 vaccination will favor the emergence and spread of dangerous variants of the virus. While viral evolution is a legitimate concern, these changes often have no effects on viral functions or result in defective or weakened versions of the original virus. Still, some mutations may confer the virus with an improved ability to infect cells or cause severe disease.

However, there isn’t evidence that COVID-19 vaccination will lead to more virulent variants of the virus than natural evolution already causes in unvaccinated populations[5]. The three circulating variants originated in the U.K., South Africa, and Brazil, which are particularly concerning because they seem to spread more easily and quickly than previous ones, all evolved naturally in unvaccinated populations.

Several studies suggest that long-lasting infections favor the development of new mutations. COVID-19 vaccines may help disrupt this process by preventing people from suffering prolonged illness, contrary to the hypothesis proposed by Vanden Bossche.

Furthermore, if COVID-19 vaccines are proven effective at preventing infection and transmission, as the available evidence increasingly indicates, they would also reduce the spread of emerging variants. In fact, history has shown that mass vaccinations are effective in curbing disease outbreaks. Such was the strategy deployed during the 1989 measles outbreak in the U.S., as well as the general strategy to control mumps outbreaks in the U.S. Furthermore, these mass vaccinations didn’t result in more dangerous variants of the measles or mumps virus that led to a worse outbreak, which would have been the case if Vanden Bossche’s hypothesis was true.

COVID-19 vaccines likely offer protection against emerging variants

Claim (Unsupported): “all these kinds of highly infectious variants, it’s very clear, that this is driving immune escape and will ultimately drive resistance to the vaccines”

It remains unclear how new emerging variants might affect the course of the COVID-19 pandemic and whether such changes will alter the real-world effectiveness of vaccines. Eventually, some emerging variants could enable the virus to escape the immune response elicited by COVID-19 vaccines or natural infections. Such variants may spread easier and faster among the population, causing a resurgence of COVID-19 cases.

Vanden Bossche claimed that mass COVID-19 vaccination would precipitate immune escape, allowing the spread of “vaccine-resistant” variants of the virus. While resistance to vaccines has emerged before, this occurs only rarely[6]. Contrast this with the current variants of concern that researchers have observed, which all evolved naturally from infected individuals. Vanden Bossche provided no evidence indicating that COVID-19 vaccines pose a greater risk of immune escape than that mediated by uncontrolled viral spread and natural infection. And as mentioned previously, earlier mass vaccination campaigns against childhood diseases like measles effectively curbed disease outbreaks and didn’t result in worse outbreaks occurring. This observation contradicts his implication that this risk of COVID-19 vaccination outweighs its benefit.

The antibodies elicited by COVID-19 vaccines showed lower efficiency in neutralizing some of the circulating variants in the laboratory[7], but the effect of this reduction in the real-world effectiveness of COVID-19 vaccines remains unclear. COVID-19 vaccines produce a strong antibody response against the virus, and researchers don’t know the minimum antibody levels that confer protection against COVID-19 yet. Therefore, reduced vaccine efficacy against these variants wouldn’t necessarily render COVID-19 vaccines ineffective. Furthermore, vaccines trigger other immune responses apart from antibody production, such as T-cell response, that may not be affected by viral variants[8,9].

The evidence so far indicates that the COVID-19 vaccines in use provide protection against viral variants. Preliminary data from Israel showed that vaccination with the Pfizer-BioNTech COVID-19 vaccine led to a 77% reduction in COVID-19 cases and 68% in hospitalizations, even though the B.1.1.7 variant, first detected in the U.K., was dominant in the country[10].

Clinical trials with the Johnson & Johnson COVID-19 vaccine and the Novavax vaccine candidate showed that these vaccines were less effective against the B.1.351 variant that emerged in South Africa, but they still reduced the risk of COVID-19 hospitalization by 50% in vaccinated individuals. These results suggest that COVID-19 vaccines might be effective against new emerging variants as well.

According to experts, the key to minimizing immune escape is a rapid vaccine rollout, combined with active surveillance of the emerging variants and their potential impact on transmission and disease. This approach allows researchers to anticipate if updating current vaccines is necessary.

Indeed, the current state of vaccine technology permits scientists to rapidly modify vaccine formulations to improve their efficacy against emerging variants. In late February, Pfizer and BioNTech and Moderna announced their plans to test a booster version of their COVID-19 vaccines specifically targeting the South African B.1.351 variant. The development and authorization of these new formulations would also be faster than that of the original COVID-19 vaccines, facilitating a speedier rollout if needed.

Vaccination doesn’t suppress the natural immune response against future infections

Claim (Incorrect): “your innate immune system […] will be outcompeted by this antigen-specific antibodies for binding to the virus, and that will be long-lived, that is a long-life suppression, and you lose every protection against any viral variant or coronavirus variant”

Vanden Bossche’s claim that COVID-19 vaccination would suppress a vaccinated individual’s natural immune response against future infections with COVID-19 or other coronaviruses is incorrect.

The role of the innate immune response in COVID-19 infections is not fully understood. The adaptive immune system, which is responsible for targeted responses to specific disease-causing microorganisms, comprises two functional arms: humoral and cell-mediated immunity. Vaccination protects people from natural infection mainly by stimulating the humoral immune response, which produces antibodies and establishes immunological memory against a specific pathogen. This enables the body to respond swiftly and effectively upon encountering a natural infection by that pathogen in the future.

Vanden Bossche claimed that vaccine-induced immunity will suppress innate immunity against the virus that causes COVID-19 and other coronaviruses. His claim refers to the natural antibodies that individuals produce constantly without any known prior exposure to a disease-causing virus or bacteria[11]. Natural antibodies are part of the innate immune response, which acts as a first-line immune defense against infections.

However, Vanden Bossche didn’t provide any evidence supporting his claim or proving that natural antibodies have a role in protecting against COVID-19.

Experts have warned that natural infection poses great health risks, even for healthy young people. In contrast, COVID-19 vaccines are safe and highly effective at protecting against the disease. While the efficacy of COVID-19 vaccines against the new emerging variants is lower compared to the original strains, they still protect against the disease caused by these variants. Therefore, high vaccination coverage remains critical to control the COVID-19 pandemic and prevent hospitalizations and deaths.


Vanden Bossche’s allegations that stopping COVID-19 vaccination is the only way to avoid the development of vaccine-resistant variants of the virus is misleading and based on speculations. Current data shows that COVID-19 vaccines effectively prevent severe disease and likely reduce COVID-19 transmission to some degree. Preliminary evidence indicates that COVID-19 vaccines partially protect against the new variants. Furthermore, vaccine technology allows scientists to rapidly reformulate vaccines to improve their efficacy against emerging variants if needed. COVID-19 vaccines are a critical tool to control the pandemic.


The blog Deplatform Disease provided a detailed point-by-point rebuttal of Vanden Bossche’s claims.

CORRECTION (7 Apr. 2021):

We removed a reference to a study on the relationship between immunization and natural antibodies, which was incorrectly described in the review.


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