The best hope for ending the covid-19 pandemic is a vaccine. There is
no shortage of candidates. The World Health Organisation is tracking 34 in
various stages of development.
How well they will work, though, is another matter. On September 9th AstraZeneca,
a drug firm, announced it was pausing its trials after a participant fell ill.
Such pauses are common in vaccine development, a discipline in which effort does
not always bring reward. Despite much research, only an imperfect vaccine is
available for dengue fever (it has limited efficacy and can cause nasty
side-effects).
In 1987 the first trial of an HIV vaccine began in Maryland. Three decades later,
the cupboard remains bare. The news about covid-19 in two new papers is more
encouraging.
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.