This week in Covid-19 news: Biden attempts to reassure, Cuba makes vaccine progress and governors are under fire.

In his first trips as president, President Biden traveled to Wisconsin and Michigan to promote his vaccination rollout plan and the $1.9 trillion relief bill he hopes can restore the American economy.

After an optimistic vow on Tuesday that any American who wanted a vaccine “could have one by the end of July this year,” Mr. Biden was asking for patience on Friday, saying the United States could be“approaching normalcy” by the end of the year. The week ended as winter storms hitting much of the country delayed the delivery of six million vaccines.

Mr. Biden addressed the virtual G7 summit and said that his administration would make good on a U.S. promise to donate $4 billion to the global vaccination campaign over the next two years. Mr. Biden’s engagement in the global fight against the pandemic is in stark contrast to the approach of former President Donald J. Trump, who withdrew the United States from the World Health Organization.

In other news this week:

• Israel has raced ahead with the fastest Covid vaccination campaign in the world, inoculating nearly half its population with at least one dose. Now, new government and business initiatives are moving in the direction of a two-tier system for the vaccinated and unvaccinated, raising legal, moral and ethical questions.

• Cuba is getting closer to achieving the mass production of a coronavirus vaccine invented on the island. If the vaccine proves safe and effective, it would hand the Cuban government a significant political victory — and a shot at rescuing the nation from economic ruin.

• Life expectancy in the United States fell by a full year, the federal government reported Tuesday. The report also showed a deepening of racial and ethnic disparities between Black and white Americans. Life expectancy of Black population declined by 2.7 years in the first half of 2020. Another study, released Tuesday, showed that Latino and Black residents of New York City have fallen behind in vaccination rates.

• Two developments this week could potentially expand access to the Pfizer Covid-19 vaccine: The vaccine works well after one dose, and doesn’t always need ultracold storage. A study in Israel showed that the vaccine is 85 percent effective 15 to 28 days after receiving the first dose, raising the possibility that regulators in some countries could authorize delaying a second dose instead of giving both on the strict schedule of three weeks apart. And Pfizer and BioNTech also announced on Friday that their vaccine can be stored at standard freezer temperatures for up to two weeks.