Covid-19: Pfizer to seek approval for booster shot and may pursue trial for 'updated' vaccine

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  • Pfizer says a third shot of its vaccine may dramatically boost immunity and increase protection against the newer coronavirus variants.
  • The company said it will submit data about its booster dose to the US FDA and apply for emergency use authorisation.
  • It is also planning a new trial to test an updated version of its two-dose vaccine that targets the Delta variant. 

Pfizer and BioNTech plan to file for US emergency use authorisation for a booster dose of their Covid-19 vaccine, the company announced on Thursday. This comes in light of evidence that people are at risk of being infected with the highly contagious Delta variant six months after being vaccinated, but that a booster shot may ensure the highest levels of immunity against the virus.

“As seen in real-world data released by the Israel Ministry of Health, vaccine efficacy in preventing both infection and symptomatic disease has declined six months post-vaccination, although efficacy in preventing serious illnesses remains high,” it said.

The ministry further explained: “During this period the Delta variant is becoming the dominant variant in Israel as well as many other countries … That is why we have said, and we continue to believe that it is likely, based on the totality of the data we have to date, that a third dose may be needed within six to 12 months after full vaccination.”

The Delta variant, which was first identified in India, has spread to more than 85 countries worldwide. It has become the dominant form of the SARS-CoV-2 virus in many countries including the US, UK, Indonesia, and South Africa. 

Dr Bha Ndungane-Tlakula, Country Medical Director at Pfizer South Africa told Health24 in June that the company will monitor trial participants from their landmark Covid vaccine study for two years after their second dose to learn more about the vaccine’s protection against Covid-19. 

He added: “We are also studying a booster dose and prototype vaccine with a variant sequence for use against new strains that may emerge.”

Is a booster really necessary?

Recent evidence published in the journal Nature showed that the initial two doses of the vaccine elicited “strong immune responses” against the Delta variant, but the company wants to test whether a third dose will boost responses even further. 

According to early trial data, when the booster is given six months after the second dose, it has a "consistent tolerability profile" and neutralises an immune response. The booster dose is still undergoing trials and the company plans to share their data with the US Food and Drug Administration (FDA) in August and file for emergency use authorisation shortly thereafter.

“We have seen encouraging clinical trial data in a small number of participants in our study examining a third dose of the current Pfizer-BioNTech Covid-19 vaccine,” the company said in a Tweet

New trial to begin in August

In addition to the booster dose, the drug company also said that they were developing an updated version of the vaccine that targets Delta specifically. The first batch of the messenger RNA (mRNA) for the new trial has already been manufactured and clinical studies are expected to kick off as early as August 2021, subject to approval, they said.

"While Pfizer and BioNTech believe a third dose of [the vaccine] has the potential to preserve the highest levels of protective efficacy against all currently known variants, including Delta, the companies are remaining vigilant and are developing an updated version of the Pfizer-BioNTech Covid-19 vaccine that targets the full spike protein of the Delta variant."

This vaccine is currently being administered in South Africa. People aged 35 to 49 years will be able to register for vaccination from 15 July, acting Health Minister Mmamoloko Kubayi announced on Friday.

As of 8 July, 378 403 people have been fully vaccinated with the Pfizer vaccine, while 875 575 people have received the single-dose Johnson & Johnson vaccine, News24 reported.  

*For more Covid-19 research, science and news, click here. You can also sign up for our Daily Dose newsletter here.

READ | Covid-19 vaccine safety: We speak to Pfizer's medical director in SA – Part 1

READ | Covid-19 vaccine safety: We speak to Pfizer's medical director in SA – Part 2

READ | Covid-19 vaccine myths debunked: Get the facts here

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