COVID-19: a new human vaccine trial begins, and other top science stories of the week

Intensive testing in the small Italian town of Vo’ has offered further evidence that a large proportion of people with COVID-19 have no symptoms. Researchers from the University of Padua tested over three quarters of the town’s residents for viral RNA in two surveys at the beginning and end of the initial two-week lockdown, discovering that 43% of people with COVID-19 reported no fever or other symptoms.

Their findings (not yet published in a journal) also show no significant difference in the amount of virus detected between those with symptoms and those without, suggesting both groups were similarly infectious.

Contact tracing of newly infected individuals at the end of the two-week period revealed that most new infections arose in the community before the lockdown or from asymptomatic cases within households during the lockdown.

Given that pre-symptomatic and asymptomatic individuals play a key role in COVID-19 transmission, the scientists behind the study say it will be difficult to control the spread of the disease without strict social distancing measures.

As humanity rushes to find a vaccine for COVID-19, research groups worldwide are making small but significant breakthroughs that could pave the way to a human vaccine in the months ahead. There are at least 70 potential Covid-19 vaccines under development , many of them already being tested in animals and a handful in humans.

This week, an experimental vaccine was shown to safely protect macaque monkeys from developing COVID-19.

In their unpublished paper, a team of Chinese medical scientists describe how their vaccine helped the inoculated animals to produce antibodies against COVID-19. In the study, they injected rhesus macaques with varying doses of a vaccine comprised of inactivated particles of SARS-CoV-2 before exposing them to the virus.

After one week, the monkeys that were given a high dose had no detectable virus in their respiratory system. Those on a lower dose displayed some signs of COVID-19 infection however these were significantly less pronounced than in the unvaccinated monkeys.

While it is not yet agreed what the best animal model for studying COVID-19 infections is, the researchers suggest that these results using macaques appear promising and hope to begin human trials of their vaccine later this year.

Human trials of a new vaccine for COVID-19 began this week, led by researchers at the University of Oxford, making it one of the first vaccines to be tested in humans – behind China and the United States.

The vaccine candidate, called ChAdOx1 nCoV-19, is made from a harmless chimpanzee virus that has been genetically engineered to carry part of the coronavirus.

The team will test safety and maximum doses of the vaccine in a small group of people at first but hope to scale up to a randomized control trial with 500 people by next month.