Why Johnson & Johnson shots were paused — and why that’s so confusing

The US rollout of Johnson & Johnson’s single-dose Covid-19 vaccine was halted Tuesday as regulators race to investigate rare blood-clotting complications linked to the shot. The move may force thousands of people scheduled to receive the shot this week to scramble for an alternative.

Both the Food and Drug Administration and the Centers for Disease Control and Prevention recommended a pause in distributing the vaccine after six reported cases of cerebral venous sinus thrombosis (CVST). These clots block blood flowing out of the brain and can quickly turn deadly.

The complications were found in women between the ages of 18 …

How to Double the Vaccination Pace

The development of the Covid-19 vaccines happened with great urgency, for obvious reasons.

One of the timesaving techniques by Moderna and Pfizer involved scheduling the two vaccine doses fairly close together — just three or four weeks apart — during the research trials. The companies did not test multiple gaps between the two shots to see which was the most effective. They each chose a short gap to finish the trials as quickly as possible.

The decision made a lot of sense. It allowed the U.S. mass vaccination program to start in December, rather than pushing it back a few

Could the Pandemic Prompt an ‘Epidemic of Loss’ of Women in the Sciences?

Like many women during the pandemic, Alisa Stephens found working from home to be a series of wearying challenges.

Dr. Stephens is a biostatistician at the University of Pennsylvania, and the technical and detail-oriented nature of her work requires long uninterrupted stretches of thought. Finding the time and mental space for that work with two young children at home proved to be an impossibility.

“That first month was really hard,” she recalled of the lockdown. Her infant daughter’s day care was closed, and her 5-year-old was at home instead of at school. With their nanny unable to come to the

After Nuclear Site Blackout, Thunder From Iran, and Silence From U.S.

JERUSALEM — The last time the centrifuges crashed at Iran’s underground nuclear fuel-production center at Natanz, more than a decade ago, the sabotage was the result of a joint Israeli-American cyberattack intended to slow Tehran’s progress toward nuclear weapons and force a diplomatic negotiation.

When they crashed again this weekend, the White House asserted that the United States had no involvement.

The operation raised the question of whether Israel was acting on its own to strike Iran and undermine American diplomacy as the Biden administration seeks to reconstitute a nuclear agreement. Or, alternatively, whether Israel was operating in concert with