Rising chorus of concern over Sputnik V vaccine stems from opaque development and lack of mass-testing.

In 1977 Scott Halstead, a virologist at the University of Hawaii, was studying dengue fever when he noticed a now well-known but then unexpected feature of the disease.

Animals that had already been exposed to one of the four closely-related viruses that cause dengue and produced antibodies to it, far from being protected against other versions became sicker when infected a second time, and it was the antibodies already produced by the first infection that were responsible, allowing the second infection to hitchhike into the body.

The effect was called antibody-dependent enhancement (ADE). The reason it matters today, in the midst of the coronavirus pandemic, is because unexpected glitches like ADE are the kind of problems vaccine developers look for in phase 3 testing of vaccines – testing which has yet to be carried out on Russia’s newly-approved Sputnik V vaccine.

ADE “is a genuine concern”, virologist Kevin Gilligan, a senior consultant with Biologics Consulting, told Nature Biotechnology in June. “Because if the gun is jumped, and a vaccine is widely distributed that is disease enhancing, that would be worse than actually not doing any vaccination at all.”

This week, following Russia’s announcement that it is pushing ahead with mass production of Sputnik V and mass inoculation , the fears expressed by the likes of Gilligan became a chorus, underlining the genuine concerns among scientists that Russian researchers had jumped the gun.

Even as Russia insisted that claims that the vaccine was unsafe were groundless, criticism continued to build.

Among those mentioning ADE as a concern was Danny Altmann, professor of immunology at Imperial College.

Part of the problem, Altmann points out, is that the work behind Russia’s vaccine development has been so opaque that no one really knows how safe or even how effective it will be.

“I don’t think the Russian researchers have done anything wrong,” he told the Guardian, “but I think they’ve jumped the gun,” he added reflecting Gilligan’s language.

“If we are talking about safety then you have to be looking at issues like ADE, which was a concern that scuppered some efforts to develop a Sars vaccine, where it exacerbated an asthma-like response in lungs.”

It is not just the potential for issues such as ADE that concerns people like Altmann, who is optimistic that the hunt for a vaccine for Covid-19 is not “intractable”.

He says the ideal approach would have been to compare 150 or so different vaccine candidates transparently, using the same testing criteria, to ensure the world gets the best vaccine, not simply the first.

“No two of these candidates is going be alike in terms of safety, how effective they are or how cheap they are to produce,” he said.

“The reason we’re crying out for transparency and peer review is because those factors are very serious. There have been too many debacles in this pandemic. This is not another occasion to blunder in. You want to line up the candidates side by side.”

The lack of effective testing throws up other issues….

Image Credit:    Amanda Scott/ Alias

Read the whole article

News This Week