Since the beginning of the pandemic, there has been much discussion about vaccines, their efficacy, the antibodies generated after its administration and after passing COVID, and how long their protection against the virus would last.

Vaccines against SARS-CoV-2 have proven to be effective in preventing death from severe respiratory syndrome caused by COVID, as well as reducing the incidence of asymptomatic infection.

And although initially the vaccines suggested sustained protection over time, it is widely known that humoral immunity does not last forever, what we did not know was exactly how long the antibodies would last in the body once we have passed the disease or have been vaccinated. 

For this, we had to wait for time to pass and monitor the status of these antibodies.

This is what a research group from Beth Israel Deaconess Medical Center did with 61 participants vaccinated with Moderna, Pfizer or Janssen vaccines.

After this research, it was discovered that between the 2nd and 4th week, the maximum immunity to the SARS-CoV-2 virus, which causes COVID, was reached in the mRNA-based vaccines (Pfizer and Moderna) and that the antibodies produced against these vaccines decreased after the 6th month and that by the 8th month this decrease was even greater.

In addition, in general, more antibody response was found in those vaccinated with the Pfizer vaccine than in those vaccinated with Moderna.

The Janssen vaccine, based on a viral vector instead of mRNA, initially induced a lower antibody response than the other two vaccines, but, nevertheless, the antibody titer was more sustained over time, remaining relatively stable 6 months later.

In another study by Cohn et al. (2021) in 780,225 US veterans (65 years and older) from February to October 2021, the effectiveness of the vaccines against SARS-CoV-2 infection was seen to drop sharply in those months from 87.9% to 48.1% for the Pfizer and Moderna vaccines. In the case of the Janssen vaccine, this effectiveness against infection dropped even further, to 13.1%.

Regarding the effectiveness of the vaccine as protection against death from SARS-CoV-2, in the summer of 2021, with the rise of the Delta variant in the U.S., a reduction in its protection in veterans has already been observed, which has several explanations:

On the one hand, while studies conducted on the variants and the protection against them by the 3 vaccines (Pfizer, Moderna and Janssen), indicated that it was relatively high for many of the variants that have been emerging since the virus entered our lives, they also told us that they did not manage to protect us as much as they did against the original virus. 

On the other hand, we must bear in mind that the immune systems of older people tend to be less efficient and slower; it has been proven that with age, antibody levels drop as the number of B lymphocytes that act in the immune response decreases.

Finally, what we mentioned at the begining in the Beth Israel Deaconess Medical Center study: the decline in antibodies that occurs naturally in all people over the months.

And just in case we needed more proof that vaccine protection decreases over the months, we only have to look at what has happened in other countries, as in the case of Israel, which in mid-June suffered an increase in the number of cases produced by the Delta variant.

Faced with this spike and having a high number of vaccinated population, the Israeli authorities at that time decided to provide a new dose of Pfizer vaccine in July to those over 60 years of age and in August to those over 50, which has led to a decrease in cases of infection and severe cases in people with an extra dose.

During these months, Israel has been (and continues) vaccinating the rest of its population with another dose, even allowing in October 2021, after the approval of a panel of experts of the FDA (Food & Drugs Administration), the vaccination of children between 5 and 11 years of age with the Pfizer vaccine. 

The Israeli case has served as a precedent for other countries to follow in their footsteps and administer new booster doses months after vaccination. vacunación. 

In Spain, for example, this new vaccination campaign began at the end of October 2021 for people over 70 years of age and people with severe immunosuppression. It is administered in conjunction with the influenza campaign.

It is expected that a third dose will gradually be administered to the rest of the population.

From Life Length, we remind you that, although the vaccine reduces the possibility of serious illness and death, it does not prevent 100% of the contagion, so we must follow the safety and hygiene measures and perform a COVID test when in doubt.

If you are not yet vaccinated, we call for social responsibility; get vaccinated so that the virus does not continue to spread so easily and to protect those who, due to their health conditions, are not lucky enough to be able to do so. 

If you get vaccinated you not only protect yourself, you protect us all.