Two studies conducted on Wednesday offer some hope that humans can develop protective immunity against the novel coronavirus — COVID-19.
The study was published in a journal of science, after a prototype vaccine was tested whether infection with SARS-CoV-2 — the strain of coronavirus that causes COVID-19 — provides immunity against re-exposure.
Two experiments were conducted on rhesus macaque monkeys to see whether they develop immunity against natural infection or from a vaccine.
In the first experiment, carried out by the researchers, nine adult rhesus macaque monkeys were infected with the virus. The monkeys developed COVID-19 symptoms but created protective antibodies and recovered after a few days.
To test their newly developed immunity, they were re-exposed after 35 days, what is called a “re-challenge”, and the monkeys showed no symptoms.
The researchers of this experiment cautioned that further research is needed because of the great difference between humans and monkeys.
“Rigorous clinical studies will be required to determine whether SARS-CoV-2 infection effectively protects against SARS-CoV-2 re-exposure in humans,” they said.
The second study, involving many of the same researchers and led by Jingyou Yu, involved vaccinating 35 adult macaques with DNA vaccine candidates designed to generate protective antibodies.
They were exposed to coronavirus six weeks later and had developed levels of antibodies in the blood which are sufficient to neutralise it, the study found.
The levels of antibodies were similar to those seen in humans recovering from the virus, providing hope that an effective human vaccine can be developed.
“Further research will need to address the important questions of the durability of protective immunity and the optimal vaccine platforms for a SARS-CoV-2 vaccine for humans,” the authors of the study said.