Moderna vaccine protects monkeys against Covid-19

WASHINGTON: US biotech firm Moderna’s Covid-19 vaccine induced a robust immune response and prevented the coronavirus from replicating in the noses and lungs of monkeys, a study in the New England Journal of Medicine said on Tuesday.

The fact that the vaccine prevented the virus from replicating in the nose is seen as crucial in preventing it from being transmitted onward to others.

The same outcome did not occur when the University of Oxford’s vaccine was tested on monkeys, though it prevented the virus from entering the animals’ lungs and making them sick.

In the Moderna study, three groups of eight rhesus macaques received either a placebo or the vaccine at two different dose levels - 10 micrograms and 100 micrograms. All vaccinated macaques produced high levels of neutralising antibodies that attack a part of the Sars-CoV-2 virus used to invade cells.

Monkeys receiving both dose levels produced these antibodies at levels higher than those found in humans who have recovered from Covid-19.

The authors reported that the vaccine induced the production of a different immune cell known as T-cells that may have helped boost the overall response.

A major concern is that vaccines under development could backfire by amplifying the disease. So-called vaccine-associated enhancement of respiratory disease has been linked to the production of a specific type of T-cell known as Th2. But these cells were not produced during the experiment, suggesting this vaccine won’t backfire.

A vaccine capable of stopping the virus in the lungs will prevent the disease from becoming severe, while stopping the virus from replicating in the nose would lessen transmission.

The Moderna vaccine uses genetic material in the form of viral RNA to encode the information needed to grow the SarsCoV-2 spike protein inside the human body to trigger an immune response.