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Covid-19 vaccine: Pfizer trial lacks Asian data
A panel of independent experts set up by the US Food and Drug Administration voted 17-4 on Thursday in favour of granting emergency use authorization (EUA) to Pfizer and its German partner BioNTech’s covid-19 vaccine
A panel of independent experts set up by the US Food and Drug Administration voted 17-4 on Thursday in favour of granting emergency use authorization (EUA) to Pfizer and its German partner BioNTech’s covid-19 vaccine.
However, the US company’s phase 3 data published in the New England Journal of Medicine (NEJM) on Thursday, as well as the regulator’s briefing document for the vaccine, showed a lack of data on Asian participants, a potential concern considering that Pfizer has asked for a clinical trial waiver in its application for an emergency licence in India.
A spokesperson for Pfizer said the term Asians in the data refers to ethnicities across the Asian continent, including Indians.
Only 4.3% of the global phase 3 trial participants recruited by the US firm were Asian, while the efficacy rate for the diverse ethnic group was 74.4%. In contrast, the company’s overall efficacy was 95% for a cohort, which comprised 83% whites, according to the documents published by the US FDA.
“We know in the past there have been challenges in vaccination when they have been taken from the Western context to LMIC (low- and middle-income countries) context. It is always better to have local data, and that is something they should be asked for,” said Anant Bhan, a researcher in global health, bioethics and health policy.
Pfizer’s phase 3 trial was held at more than 150 clinical trials sites globally, and while the majority of them were in the US, 22 of these sites were spread across Germany, Turkey, South Africa, Brazil and Argentina, data in the NEJM, a peer-reviewed journal, showed.
“India has a very large and extremely heterogeneous population, and we need to know the efficacy on people across the country. Even the safety profile is unknown in such a diverse population. As we saw when Pfizer provided data on various ethnicities from its efficacy study, its mRNA vaccine had 74% efficacy among Asians and not the 95% seen overall. That tells you there are differences in efficacy, depending on ethnicity,” said Davinder Gill, a vaccine expert based in Massachusetts, US, adding that vaccine developers need to conduct large scale trials in India as it is extremely diverse and heterogeneous.
On the other hand, Suneela Garg, director of the department of community medicine at Maulana Azad Medical College, said the vaccine was tested on a wider demography in the US and the efficacy was largely consistent and that despite the lower efficacy in Asians, it was still better than the benchmark 50% set for covid vaccines.
“Any efficacy rate that is over 60% is good enough. Even flu vaccines have similar efficacy as this mRNA vaccine. But we have to remember that this vaccine has more side-effects than the flu vaccine,” Garg said.
Phase 3 trials are usually conducted over a diverse area and group of people. However, during this pandemic, Pfizer has sought a waiver on clinical trials in India.
In a statement to Mint, a spokesperson for Pfizer said the company’s cohort in the phase 3 study was racially and ethnically diverse, with approximately 42% of global participants and 30% of US participants having racially and ethnically diverse backgrounds.
“Efficacy was consistent across age, gender, race and ethnicity demographics. The observed efficacy in adults over 65 years of age was over 94%,” the spokesperson said.
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First Published:11 Dec 2020, 11:31 PM IST
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