Coronavirus Briefing: What Happened Today

• The world’s known Covid death toll passed four million.

• Africa recorded its “worst pandemic week” yet, with cases surging and vaccines scarce, the W.H.O. said.

• California’s Capitol building revived a mask rule after an outbreak infected four fully vaccinated people.

• Get the latest updates here, as well as maps and a vaccine tracker.

What we know about Lambda

In recent weeks, headlines and social media posts have begun to sound the alarm about the Lambda variant, which was first detected in Peru late last year. The variant has spread quickly throughout Latin America, and the W.H.O. designated it a “variant of interest,” meaning that experts suspect it could be more dangerous than the original strain.

But there’s still a lot of mystery surrounding the variant, and the level of risk it poses. Here’s what we know and don’t know about Lambda.

What we know

Where it’s shown up: As of mid-June, Lambda had been reported in 29 countries, territories or areas. In Peru, the variant has been detected in 81 percent of coronavirus samples sequenced since April, according to the W.H.O. In Chile, it has been detected in 31 percent of samples tested to date. Isolated cases have also been reported in a number of other countries. In the U.S., it has accounted for less than 1 percent of samples.

The mutations: Lambda contains eight notable mutations. Some of these mutations are present in other variants and may make the virus more infectious or help it evade the body’s immune response.

What we don’t know

Whether it can evade vaccines: Preliminary laboratory studies offer both concern and reassurance. In these studies, research teams found that antibodies induced by the Pfizer, Moderna and CoronaVac vaccines are less powerful against Lambda than against the original strain, but that they are still able to neutralize the virus. Antibodies are also not the body’s only defense against the virus. Even if they’re less potent against Lambda, other components of the immune system, like T cells, may also provide protection. Scientists said that the findings from these studies suggested that these vaccines should still work against Lambda.

Potency: After revising its death count in late May, Peru now has one of the highest death tolls for its population in the world. That has led some people to speculate that Lambda may be the culprit. However, Peru’s surge and high death toll may have more to do with the country’s deep-rooted inequality and fragile heath care system. We still don’t know whether Lambda causes more severe forms of Covid-19 than other variants.

Transmissibility: As with several other variants, the preliminary results indicate that Lambda binds more tightly to cells than the original strain of the virus does, which may make it more transmissible. But more research is needed.

Despite the worry, no evidence so far suggests that Lambda will outcompete Delta, the highly transmissible variant that’s now dominating most of the world.

“I think some of the interest is just based on the fact that there’s a new variant, and it has a new name,” said Nathaniel Landau, a microbiologist at the New York University Grossman School of Medicine who is studying the new coronavirus variants. “There’s no reason to think that this is now something worse than Delta.”

New Olympics restrictions

The Tokyo Olympics begin on July 23, and Japan does not have the virus under control.

In response to a sudden spike in cases — Tokyo reported 920 on Wednesday, its highest number since May — authorities announced a state of emergency that will begin Monday and last through the end of the Games, which conclude on Aug. 8.

Organizers will also bar most spectators, a reversal of an earlier announcement that they planned to welcome domestic fans. A few events, like the marathon, will be held in locations not affected by the new state of emergency, allowing for the possibility that some fans will be allowed to attend.

For months, the Japanese public has expressed widespread opposition to the Games, which many fear could become a petri dish for new variants or outbreaks. Recent polls show that a large majority supports canceling or further delaying the Olympics.

And although Japan has had a relatively mild pandemic experience, its vaccine rollout — now at more than a million doses a day — got off to a slow start. According to Reuters, the country has administered enough doses to vaccinate about 21 percent of its population.

But the organizers show no sign of stopping. Officials have long insisted that they can safely hold the Games, which the pandemic already delayed by a year. And in a sign of the event’s inevitability, the International Olympic Committee president, Thomas Bach, arrived in Tokyo on Thursday.

The Delta variant

• How does the variant dodge the immune system? Scientists have found clues.

• Infections of the variant in France have doubled over the last week, leading officials to warn of a “rapid” fourth wave of the virus, Euronews reports.

• As the variant surges in the U.S., experts are warning of a dangerous fall unless virus restrictions like indoor mask wearing and capacity limits are reimposed, CNBC reports.

See how the vaccine rollout is going in your county and state.

What else we’re following

• A new study found genetic variations in Covid patients that could point to better drug treatments.

• Germany pledged to donate its unwanted AstraZeneca and Johnson & Johnson vaccines to developing countries.

• The prime minister of Luxembourg, who was hospitalized with Covid-19, has returned home.

• Haiti’s political turmoil may hamper efforts to contain the virus there, the W.H.O. said.

• France advised its citizens not to vacation in Spain or Portugal because of recent increases in cases there.

• Britain’s health secretary said he foresaw record cases after the coming reopening — July 19, or “Freedom Day” — but said the vaccine “severely weakened” the link from illness to hospitalizations.

• The Minneapolis Fed announced a vaccine requirement for employees.

• Starved for public displays of affection, some are taking New York’s reopening as a cue to start making out everywhere.

What you’re doing

I’ve been coping in creative ways since two of my five senses were erased by Covid-19. I made it 10 months without contracting the virus. I was so careful and proud of it. Then in late January, despite never having let my guard down, bam! It was my turn. It didn’t hit me too severely. It was just headache, fatigue, congestion, and loss of taste and smell. But the taste and smell haven’t come back correctly, over five months later. No looking forward to the next meal. No tingles upon smelling traces of flowery or woodsy scents on my early morning commute (now that I’m not the only one on my bus, to add salt to the wound). Even throughout the pandemic, I remained an organized optimist, but this left me just so dull.

— Heather M., Staten Island, New York

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