COVID-19 protection can wane within 3 months of second dose of Pfizer vax

By Mark Waghorn via SWNS

Protection against Covid from the Pfizer vaccine can wane within three months of getting a second dose, according to new research.

Risk of infection increases gradually after 90 days - rising nearly threefold after six months.

The results, published in The BMJ, suggest a third 'booster' jab is required, say scientists.

Corresponding author Dr. Ariel Israel, of Leumit Health Services in Tel Aviv, said: "This large scale population study showed protection offered by two injections of the Pfizer vaccine - 21 days apart - decreased after several months.

"The risk of infection in adults who received two vaccine injections increased with time elapsed since vaccination compared with individuals vaccinated in the last 90 days."

His team analyzed the electronic health records of over 80,000 men and women in Israel.

They received a PCR test at least three weeks after their second injection - and had no evidence of previous infection.

Israel was one of the first countries to roll out a large-scale COVID-19 vaccination campaign in December 2020.

It has seen a resurgence of cases since June.

The study confirmed the Pfizer jab provided excellent protection in the initial weeks.

But it waned for some individuals with time.

Across the world, large-scale vaccination programs are helping to control the spread of the virus.

But even in countries with high vaccination rates outbreaks can occur - which scientists think is due to a gradual loss of immunity over time.

Examining patterns could provide important clues about the need for a third injection - and its preferred timing.

Almost one in ten of the study participants - 7,973 or 9.6 percent - had a positive test result.

These individuals were then matched to negative controls of the same age and ethnic group who were tested in the same week.

The rate of positive results increased with the time that had elapsed since a second dose.

For example, across all age groups 1.3 percent of tested positive 21 to 89 days afterwards.

But this increased to 2.4 percent after 90 to 119 days, 4.6 percent after 120 to 149 days, 10.3 percent after 150 to 179 days and 15.5 percent after 180 days or more.

The risk of infection across all age groups was 2.37-fold higher after 90-119 days - rising to 2.66 after 120-149 days and 2.82 after 150-179 days and 180 days or more.

The researchers studied a large study of people who all received the same vaccine.

They were able to carry out detailed analysis of the data - suggesting the results are robust.

Dr. Israel said: "In individuals who received two doses of the Pfizer vaccine, protection seemed to decrease over time.

"The results suggest that consideration of a third vaccine dose might be warranted."