Third dose of Pfizer’s COVID-19 vaccine boosts immunity against Indian ‘Delta’ variant’

Athird dose of the Pfizer-BioNTech COVID-19 vaccine could offer strong protection against the Indian ‘Delta’ variant, data reveals, as a separate study finds protection provided by the vaccine could wane after six months.

New data released by the company showed antibody levels increased five-fold among people ages 18 to 55 who were given the booster shot.

The third dose was especially effective for the elderly, with antibody levels spiking 11fold among people aged 65 to 85 who had already received the standard two doses.

In the slides published online, the researchers wrote there is ‘Estimated potential for up to 100-fold increase in Delta neutralisation post-dose three compared to pre-dose three.’

The new data come at a welcome time with separate pre-print research finding that the efficacy of the Pfizer vaccine falls from 96 per cent to only 84 per cent after six months.

The Delta variant continues to spread across the country, making up at least 83 per cent of all new infections.

Pfizer produces the most commonly used vaccine in the U.S., having been administered over 190 million times, according to data from the Centre for Disease Control and Prevention (CDC).

Early adopters of the vaccine may soon have their immunity to the virus slightly diminished.

The research, which has not been peerreviewed, led by Pfizer and Syracuse University in New York finds that the vaccine was 91 per cent effective in preventing the virus for six months.

After the time span, the efficacy slightly falls to only 84 per cent.

If it continues to drop at that rate, researchers say, the vaccine could drop below 50 per cent efficacy 18 months after administration.

Those who are fully vaccinated and contract COVID are still less likely to experience serious symptoms or hospitalisation, though.

Pfizer’s vaccine was first given emergency use authorisation by the U.S. Food and Drug Administration in December and was first distributed to priority populations like the elderly and health care workers that month.

Those who received the vaccine first may have already had its efficacy drop, meaning a third dose could be required soon.

The company plans to submit its application for emergency use authorisation for the third dose to the FDA as early as August, according to slides distributed before an earnings call.

Rumbles about the potential for a third dose in the near future have been happening for months.

Dr Anthony Fauci, Director of the National Institute of Allergy and Infectious Diseases has said in the past that he expects a third dose to be needed in the coming months.

Though, he said earlier this month that he does not expect booster shots to be needed for the fully vaccinated at this time.

Fauci said earlier this week, though, that those who are vulnerable to the virus even after vaccination still may require a third dose.

If Pfizer’s findings - which are not peerreviewed - are correct, then the third dose could be a valuable tool in combating the variant.

The company’s findings also found that a third dose could be particularly effective in combating the South African Beta variant.