The good news is that the virus seems to generate a robust and fairly long-lasting immune response.
The news about covid-19 in two new papers is encouraging, reports The Economist. The first, written by a team of scientists at Decode Genetics, an Icelandic company, and published in the New England Journal of Medicine, reports antibody levels in 1,200 Icelanders who had been infected with the sars-cov-2 virus and recovered. More than 90% tested positive for antibodies twice - once immediately post-infection and again four months later. People who had suffered more serious disease, such as those who had been hospitalised, developed higher levels of antibodies. So did men and older people, both of whom are at greater risk of more severe illness.
The four-month lifespan is cheering for two reasons. Antibodies that hang around are more likely to offer immunity. That means a vaccine that provokes their production should provide reasonably long-lasting protection. They are also easier to find. That suggests that results from population-wide antibody screening programmes, which aim to chart the spread of the virus, should be fairly accurate.
In the second study, scientists led by Tao Dong, an immunologist at the Medical Research Council, in Britain, went hunting for t-cells. These get less press than antibodies, but play an equally vital role in battling infections and securing long-term protection.
As described in Nature Immunology, the researchers compared blood samples from 28 mild and 14 severely ill covid-19 patients, as well as 16 healthy donors. The paper describes a “robust” t-cell response in infected people, and could offer useful hints for refining vaccines in future.
Al Edwards, an immunologist turned biochemical engineer at the University of Reading (who was not involved with either paper), is cautiously optimistic. The immune response to the disease seems to be working roughly as expected, he says. If that continues, then vaccines developed to trigger long-lasting immunity should work.
Of course, the best hope for ending the pandemic is a vaccine (and there is no shortage of candidates) with the World Health Organisation tracking 34 in various stages of development.