The COVID-19 vaccines protect people from severe COVID-19 and don’t weaken the immune system
The COVID-19 vaccines are highly effective in preventing severe COVID-19. Over the course of several months, however, their effectiveness reduces. This has prompted booster dose programs in many countries to provide longer-lasting protection. The vaccines do not weaken the immune system, as evidenced by the significantly higher rates of hospitalization due to COVID-19 among unvaccinated people.
Misleading: The COVID-19 vaccines were primarily tested and developed to reduce hospitalizations and deaths. The vaccines have been very successful in doing this and reducing the risk of severe cases in fully vaccinated people. Even if vaccinated people are more likely to test positive for COVID-19, due to differences in behaviour for instance, this doesn’t suggest that the vaccines are ineffective.
Fails to grasp significance of observation: Vaccine effectiveness is expected to reduce over time and studies of this effect in people vaccinated against COVID-19 helped to determine the need for booster doses. These studies didn’t provide evidence that the immune systems of vaccinated people had been compromised in any way.
An article published by the website The Exposé on 22 January 2022 made a number of claims, one of which was that the COVID-19 vaccines lead to a weakened immune system. However, as we will explain below, this is based on misleading and misinterpreted figures. The vaccines provide protection against severe COVID-19 and a booster dose is used to prolong their effectiveness.
The Exposé is an outlet known to publish misinformation and conspiracy theories. Its previous articles were fact-checked several times by Health Feedback and were found to be inaccurate or misleading, including an article containing the repeated claim that vaccinated people are becoming immunodeficient.
The vaccines protect against severe COVID-19
One dataset cited by The Exposé came from the COVID-19 weekly surveillance report from New South Wales in Australia. Using data from 26 November 2021 to 1 January 2022, the article claimed that a higher incidence of COVID-19 among fully vaccinated people compared to unvaccinated people is evidence of weakened immune systems.
However, the vaccines were primarily intended to reduce the number of severe cases of COVID-19 that lead to hospitalization and death, not to prevent infection. In this regard, the vaccines have been highly effective. The report states:
“Among cases aged 12 years and over with no effective [vaccine] dose, 9.1% of cases were hospitalised, 1.5% of cases were admitted to ICU, and 0.3% of cases died. In comparison, among fully vaccinated cases, 1.2% of cases were hospitalised, 0.1% were admitted to ICU, and less than 0.1% died.”
This shows that vaccinated people who get infected are much less likely to suffer from a severe case, due to their enhanced immune protection against COVID-19.
The anonymous writer of the article on The Exposé calculated that vaccinated people in New South Wales were more than twice as likely to test positive for COVID-19. This was calculated by dividing the crude number of cases recorded in vaccinated and unvaccinated people by the number of people in each group. However, this doesn’t take into account underlying statistical biases in the data. It is important to keep in mind that there are likely to be systematic differences between vaccinated and unvaccinated people in terms of their likelihood to seek out testing as well as their risk of exposure to COVID-19.
For example, during the period analyzed, about only 5% of the population over the age of 12 in New South Wales were unvaccinated. Such a small, self-selecting group, like this one, is unlikely to be representative of the general population, so it is likely that there are behavioral and demographic differences, such as sex, ethnicity, deprivation, disability, and educational attainment.
Furthermore, a higher case rate among vaccinated people could be due to a wide range of reasons that are unrelated to vaccine effectiveness, including fewer restrictions on attending indoor events or wider use of tests.
The COVID-19 vaccines’ effectiveness wanes over time and benefits from a booster dose
The Exposé also used a study of vaccine effectiveness to claim that it found “that vaccine effectiveness start declining sharply within 2 weeks of the 2nd jab” and “that the vaccines offer NO medium term protection against Omicron”.
The study that The Exposé article referred to was posted as a preprint in August 2021, months before the first observation of the Omicron COVID-19 variant. It didn’t contain any information on the effectiveness of the vaccines against Omicron.
The study looked at blood antibody levels in nursing home residents and healthcare workers six months after receiving the Pfizer-BioNTech vaccine. The results showed that the initial antibody levels, two weeks after the second dose of the vaccine, were higher in the healthcare workers than in the nursing home residents. But this isn’t unexpected; a study previously observed a lower vaccine response in terms of antibody production in an older population. The nursing home study didn’t look at antibody levels before two weeks, so it wouldn’t be possible to conclude, based on that preprint’s findings, that vaccine effectiveness declined sharply within two weeks, as The Exposé claimed.
After six months, the researchers observed that antibody levels fell in both groups and that this decline was more pronounced in the nursing home residents. This provided evidence in favor of a booster vaccine program to maintain immunity against COVID-19.
It is important to note that antibodies are just one component of COVID-19 immunity. Other parts of the immune system, such as T cells, also contribute to fighting infection and their protection can last longer than antibodies.
The Exposé article also used other data sources to highlight the fall in vaccine effectiveness over the six months after being fully vaccinated. This has been widely acknowledged and is the primary reason for the introduction of the booster vaccine program in many countries.
As explained previously on Health Feedback, booster doses aren’t unusual and are used with other types of vaccines, such as tetanus, to provide longer-lasting protection. The booster dose prompts the immune system to be more prepared against the virus, so that it can quickly respond in the event of a future infection.
There is no evidence for weakened immune systems in vaccinated people
The Exposé used the statistics on waning vaccine efficiency over time and case rates in vaccinated people to suggest that there is a “new form of Covid-19 vaccine induced acquired immunodeficiency syndrome”.
Acquired immunodeficiency syndrome, or AIDS, is a specific condition that results from infection by HIV, which leads to the destruction of immune cells that causes infected people to be vulnerable to life-threatening infections and cancers. This is entirely unrelated to vaccines and The Exposé provided no evidence showing that vaccinated people are unable to fight infections or have impaired immune systems. On the contrary, vaccinated people have stronger immunity against COVID-19, which provides greater protection against severe disease.
- 1 – Dolby et al. (2021) Monitoring sociodemographic inequality in COVID-19 vaccination coverage in England: a national linked data study. medRxiv. [Note: This is a preprint that has not yet been peer-reviewed at the time of this review’s publication.]
- 2 – Canady et al. (2021) Significant reduction in humoral immunity among healthcare workers and nursing home residents 6 months after COVID-19 BNT162b2 mRNA vaccination. medRxiv. [Note: This is a preprint that has not yet been peer-reviewed at the time of this review’s publication.]
- 3 – Müller et al. (2021) Age-dependent Immune Response to the Biontech/Pfizer BNT162b2 Coronavirus Disease 2019 Vaccination Clinical Infectious Diseases.