The second Pfizer dose would be less effective in women, smokers and the elderly

Most of the COVID vaccines developed so far have proven to be particularly powerful. And the one developed by Pfizer is no exception to this reality. However, as the months go by, the effectiveness of vaccines diminishes.

Concretely, the results indicate a decrease in the immunity offered by the vaccine from the six months following the second dose. It is for this reason, moreover, that a 3rd dose is now recommended.

Factors that may explain this decline in immunity

Scientists recently discovered in Japan that there are a few main factors that may cause the vaccine’s effectiveness to decline after six months. Among these, we find in particular old age as well as smoking. Indeed, it has been noted a low level of antibodies in the elderly and those who smoke.

Also, women were more likely to experience a rapid decrease in their antibody levels, on average six months after injection of the second dose of Pfizer-BioNTech. As a guide, the study specified that: “The attenuation of antibody titers for 3 to 6 months after the second dose of BNT162b2 vaccine depends on gender, with age and smoking as risk factors for titers. ‘antibodies less than 6 months’. It is also possible to consult it on the platform medRxiv *.

More details on the research carried out

To learn more about this study, note that it involved 365 health workers who have already been vaccinated. It was carried out in a health center in Tochigi prefecture, and on 250 women as well as 115 men. It should also be noted that the median age was 44 years and that health professionals constituted 56.2% of the population analyzed.

In addition, the research work consisted among other things in comparing the antibody levels of the people studied and the peak protein of SARS-CoV-2 6 months after a second dose. Based on the data collected, the median antibody titer was approximately 539 U / mL.

More info on factors that may be causing the decline

It should be noted that the elderly had very low antibody titers, reaching even half of those presented by the agents of an average of 20 years. We can thus determine that the more the age progressed from 20 to 70 years, the more the antibody levels fell. Note that the scientists behind the study had to adjust the data. This is because a few endogenous elements such as hypertension may have influenced the results relating to age.

On the other hand, following another analysis, it appeared that only smoking had a strong correlation with lower antibody levels. “In terms of smoking, the median age-adjusted Ab titers were -97 (-277 to 184) and 56 (-182 to 342) among smokers and non-smokers, respectively”, have let scientists understand the study. On the other hand, in the case of the sex factor, it is noted that the antibody levels against SARS-CoV-2 have fallen to a median percentage of -29.4.

In fact, women had a 6.5% decrease rate, faster than men. For women, the median level of variation in the number of antibodies was -31.6% against -25.1% for men. But finally, remember that the researchers specify that individual differences not considered in the study could also have influenced the decline in immunity. And we invite you to consult this SOURCE for more details on the study.

Leave a Comment