Pfizer Vaccine’s Immunity Protection Weakens Months After 2nd Dose, Especially In Men: Study

Pfizer Vaccine’s Immunity Falls Continuously Within 6 Months After 2nd Dose

Many Singapore residents have been inoculated against Covid-19 after receiving the Pfizer-BioNTech jab that’s part of our national vaccination programme.

However, on Wednesday (6 Oct), the New England Journal of Medicine published a study that found the immunity provided by Pfizer’s vaccine falls significantly within months.

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The study also reported that antibodies in recipients decreased continuously over a 6-month period following their 2nd dose. This is especially so in men and older individuals.

Pfizer vaccine immunity decreases within months especially in men

The study, conducted on 4,868 Israeli healthcare workers, found that the immunity provided by the Pfizer vaccine fell continuously over the 6-month period after the 2nd dose.

The level of antibodies in vaccinated individuals reportedly decreased rapidly for the first 3 months before tapering down to a more moderate rate.

Interestingly, antibodies were found to be lower in men compared to women.

This is consistent throughout the months, with male participants’ antibody counts lower than their female counterparts at their peak and at the end of the study.

It was also lower amongst seniors aged 65 years or older compared to those between 18 and 45.

Additionally, immunosuppressant individuals had lower levels of antibodies in comparison to healthy individuals.

According to The Straits Times (ST), an expert said this might explain why there are breakthrough infections in vaccinated individuals.

Supported by Qatar study

Another study conducted in Qatar, also published on 6 Oct, supported the claims above.

The Qatari found that the Pfizer vaccine’s protection peaked at 77.5% in the 1st month after the 2nd dose.

Thereafter, the effectiveness declined and started dipping at an accelerated rate after the 4th month.

Between the 5th and 7th month, effectiveness plummeted to about 20%.

Despite that, the vaccine was extremely successful in preventing severe and fatal infections throughout the 6 months, reaching about 96% or higher protection in the first 2 months.

The vaccine’s protection against hospitalisation and death is also strong and more long-lasting than its protection against infection.

He added that a 3rd booster shot will help optimise protection from the vaccine, reports ST.

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Booster shots necessary

Dr Gili Regev-Yochay, co-author of the Israel study, said researchers are trying to identify the threshold of antibodies required to prevent infections, severe illness, and death.

These studies will be useful in assessing risk levels associated with different groups and determining the protective measures required.

According to ST, the US has restricted its booster recommendation only to seniors and others who might be more vulnerable.

However, they are likely to offer the 3rd dose to their entire population in the future.

Singapore’s booster exercise is also currently underway. Elderly folks above 60 can receive their boosters at any vaccination centres on a walk-in basis.

Still effective in preventing severe symptoms

The study will understandably alarm those who had gotten the Pfizer vaccine.

But it is important to note, especially as more are likely to get infected with Covid-19, that it is still effective in preventing the onset of severe symptoms.

If anything, this shows us the importance of also getting the booster shot when the time comes around for us to get it.

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Featured image adapted from BioSpace.