Johnson & Johnson’s vaccine is less effective at preventing COVID-19 than other approved vaccines are, but experts say it could still be an important tool in curbing the pandemic.

Studies on SARS-CoV-2’s milder cousins hint that our immune systems are quick to forget the viruses, but it’s unclear whether the same is true for the agent that causes COVID-19.

A handful of factors tip the scales in making a virus more likely to trigger a disruptive global outbreak. Right now, scientists tend to rank influenza, coronaviruses, and Nipah virus as the biggest threats.

A coronavirus has been commanding the headlines for months, but strains of influenza and paramyxovirus are extremely dangerous pathogens that could spark outbreaks.

Some researchers express skepticism given the lack of data about the vaccine’s safety and efficacy, and the country plans to vaccinate healthcare workers, teachers, and others even before testing is complete.

The basic reproductive R0, along with the more malleable effective reproduction number Re, are centerpieces of most epidemiological models that are informing government responses to COVID-19.

The SARS-CoV-2 pandemic has revealed the limitations of R0 as no other disease outbreak has before, at a time when policymakers need accurate forecasts.

As communities and businesses reopen amidst the pandemic, masks—in addition to other social distancing measures—are crucial for preventing new outbreaks.

An influenza virus identified in pigs in China has a concerning mix of genes, but experts say there is no way to know if it will evolve to be transmissible between humans.