What's the evidence for COVID-19 booster shots?

摘要

The United States government will roll out COVID-19 booster shots in late September to shore up protection against more transmissible variants. Other countries may follow suit. But the move is raising questions about the scientific and ethical basis for the decision, with some experts calling it premature. Americans will be eligible to receive a third dose of the Pfizer or Moderna vaccines eight months after receiving their second dose. People who received the single-dose Johnson & Johnson vaccine will probably need boosters too but are not yet eligible pending further data.