Never in the history of mankind has a potential vaccine against any pathogen reached the doorsteps of regulators for public use as quickly as in the case of Covid-19.
Since January this year, scientists in many countries have been working round-the-clock to find a vaccine that could quell the pandemic that threatened to disrupt the world.
As of now, interim analyses based on Phase 3 trials of the vaccines by Moderna, Pfizer-BioNTech, AstraZeneca-Oxford University and Russia’s Gamaleya Centre are already out and they are now queuing up for regulatory approvals in various countries before people can be inoculated.
Experts say vaccines usually take years, if not decades, to reach people and the fastest record is about four years for the mumps vaccine. But there are several factors that propelled the jet speed at which the vaccines against SARS-CoV-2 were developed.
The fact that the pathogen driving the pandemic is a coronavirus — one that was strikingly similar to others that had previously jumped from animals to people — meant that scientists could quickly tweak vaccine projects in the works for those.
Many teams pursuing vaccines for Covid-19 have previously worked on vaccines for the original SARS virus and MERS.
A molecular tweak by Dr Barney Graham and a colleague at the National Health Institute’s Vaccine Research Centre (VRC) in the US is said to have done the wonders.
They used sophisticated computer models to quickly find a way to stabilise the SARS-CoV-2 spike protein, by adding two amino acid molecules, both proline, through a technique called 2p trick.
As Graham was already collaborating with Moderna, its scientists immediately began working with the stabilised protein. And because VRC is public funded research, their protein was available to anyone else. Specialists point out that Pfizer-BioNTech, Novavax and Johnson and Johnson have also relied on the 2p-tweaked spike protein for their vaccine candidates.
One of India’s top vaccine scientists, Dr Gagandeep Kang, pointed out that readymade delivery platforms — RNA (Moderna and Pfizer), adenoviruses (AstraZeneca and Gamaleya) — only to be tailored for SARS-CoV-2 have also worked.
Vaccine development takes a lot of money, too, and governments in developed countries and international organisations ensured there was an unprecedented infusion of funds.
The US, for example, has invested US$ 8.15 billion only into vaccine research, development and manufacturing, but the UK too has supported both AstraZeneca and Pfizer.
Then flexibility shown by the regulators allowed unforeseen fast-tracking and permitted human clinical trials only after short-term animal safety data. Those in the know seem impressed with the results that these factors have led to.
“The Pfizer-BioNTech and Moderna results are solid and based on a decent number of infections,” said virologist Shahid Jameel.
“So are the Oxford-AstraZeneca results, except this curious result of better efficacy with lower dose. The Russian results are interim, based on only 7 days’ follow-up and 39 infections. We should wait for a longer follow-up.” Jameel said efficacy from controlled trial conditions generally drops a little when vaccines go in the field. “Still it will be good,” he added.
“These results tell us that most vaccines being tried will work as all are based on spike protein so overall there is a lot of optimism.” For some experts, however, there is a caveat.
Immunologist Dipyaman Ganguly said, “The concern that’s bugging immunologists like us is that the immune response induced by these will be safe for the older comorbid individuals as the immunity induced by natural infection is found to cause severe disease in this population more often.”
He insisted that any vaccine must be tested for their safety and efficacy in this population, not only in healthy young adults, as the vaccine trials usually do.