Three of COVID-19’s top science stories for the week on April 24

Intensive testing in the small Italian town of Vo ‘has offered more evidence that a large proportion of people with COVID-19 have no symptoms. Researchers from the University of Padua tested three-quarters of the city’s residents for viral RNA in two surveys at the beginning and end of the initial two-week blockade, finding 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 symptoms, suggesting that both groups were equally infectious.

Tracing contacts of newly infected individuals at the end of the two-week period revealed that most new infections arose in the community prior to closure or asymptomatic cases within households during closure.

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

As humanity races to find a vaccine for COVID-19, research groups around the world are making small but significant strides that could pave the way for a human vaccine in the coming months. There are at least 70 potential Covid-19 vaccines in development, many of them already tested on animals and some on humans.

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

In their unpublished article, a team of Chinese medical scientists describes how their vaccine helped inoculated animals produce antibodies against COVID-19.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

After a week, the monkeys who received a high dose had no detectable virus in their respiratory system. Those with a lower dose showed some signs of COVID-19 infection, however these were significantly less pronounced than in unvaccinated monkeys.

While the best animal model for studying COVID-19 infections has yet to be agreed, the researchers suggest that these results with macaques look 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 on humans, behind China and the United States.

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

Initially, the team will evaluate the safety and maximum doses of the vaccine in a small group of people, but hopes to escalate to a randomized control trial of 500 people next month.