Two studies indicate reinfection may not happen

CHICAGO: Two recently published studies hold promise over one of the most enduring questions since the outbreak of the coronavirus disease (Covid-19): does a person who has recovered from the highly contagious disease develop immunity against reinfection? US researchers have indicated that the answer may be yes – a positive sign that vaccines being developed could succeed.

The two studies in monkeys have offered some of the first scientific evidence that surviving Covid-19 may result in immunity from reinfection, the researchers said on Wednesday. Although scientists have assumed that antibodies produced in response to the new virus are protective, there has been scant scientifically rigorous evidence to back that up.

How long the protection lasts, however, still remains unclear. In one of the new studies, researchers infected nine monkeys with SarsCoV-2, which causes Covid-19.

After they recovered, the team exposed them to the virus again and the animals did not get sick.

The findings suggest that they “do develop natural immunity that protects against re-exposure”, said Dr Dan Barouch, a researcher at the Center for Virology and Vaccine Research at Harvard’s Beth Israel Deaconness Medical Center in Boston, whose studies were published in the journal Science. Several research teams have released papers – many of them not reviewed by other scientists – suggesting that a vaccine against the virus would be effective in animals.

In the second study, Barouch and colleagues tested 25 monkeys with six prototype vaccines to see if antibodies produced in response were protective. They then exposed these monkeys and 10 control animals to Sars-CoV-2. All of the control animals showed high degrees of virus in their noses and lungs, but in the vaccinated animals, “we saw a substantial degree of protection”, Barouch said.