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The weather is getting warmer. The days are getting longer. Some stores are reopening. And California is slowly easing up on the sheltering restrictions placed on us during this pandemic. In other words, we’re getting out of our homes a little more after weeks of a statewide shutdown. But this isn’t the same world we remember from before. There are new questions about personal contact and social distancing. There are fresh concerns about infection in the environment around us. The Chronicle talked to some health experts about how we can best navigate the Bay Area without contracting the coronavirus. (Whiting, 5/21)

Researchers who examined the lungs of patients killed by covid-19 found evidence that it attacks the lining of blood vessels there, a critical difference from the lungs of people who died of the flu, according to a report published Thursday in the New England Journal of Medicine. Critical parts of the lungs of patients infected by the novel coronavirus also suffered many microscopic blood clots and appeared to respond to the attack by growing tiny new blood vessels, the researchers reported. (Bernstein, 5/21)

The coronavirus primarily spreads from person to person and not easily from a contaminated surface. That is the takeaway from the Centers for Disease Control and Prevention, which this month updated its “How COVID-19 Spreads” website. The revised guidance now states, in headline-size type, “The virus spreads easily between people.” It also notes that the coronavirus, which causes the disease covid-19, “is spreading very easily and sustainably between people.” (Guarino and Achenbach, 5/21)

In new guidance for mathematical modelers and public health officials, the US Centers for Disease Control and Prevention is estimating that about a third of coronavirus infections are asymptomatic. The CDC also says its "best estimate" is that 0.4% of people who show symptoms and have Covid-19 will die, and the agency estimates that 40% of coronavirus transmission is occurring before people feel sick. (Azad, 5/22)

Sweden has revealed that despite adopting more relaxed measures to control coronavirus, only 7.3% of people in Stockholm had developed the antibodies needed to fight the disease by late April. The figure, which Sweden's Public Health Authority confirmed to CNN, is roughly similar to other countries that have data and well below the 70-90% needed to create "herd immunity" in a population. It comes after the country adopted a very different strategy to stop the spread of coronavirus to other countries by only imposing very light restrictions on daily life. (Kennedy, 5/21)

As lockdowns ease across the world, keeping the new coronavirus at bay will depend on people seeking a test or self-isolating if they suspect they have symptoms. But, five months after the virus emerged, national health authorities don’t agree on how to define those symptoms. In countries that describe the symptoms more narrowly, including the U.K. and up to last month the U.S., some people with the disease may have been unable to get tested and may have unknowingly spread the disease by mingling in the community. (Sugden, 5/22)

An investigation into a wedding-related COVID-19 outbreak in Jordan found a high transmission rate and a high rate of asymptomatic carriers, researchers from Jordan reported yesterday in Emerging Infectious Diseases. The outbreak occurred in the middle of March when Jordan had only one confirmed case, but it led to a surge of cases that a month later made up 24% of all COVID-19 cases in Jordan and helped spur a lockdown in the city of Irbid, where the wedding took place. (5/21)