Where Potential COVID-19 Vaccines Stand in the U.S.

Four vaccines for the novel coronavirus are now in late-stage testing in people in the United States. Here are some details:

  • Johnson & Johnson vaccine – The vaccine uses noninfectious adenovirus, a common cold virus, to deliver a gene from the novel coronavirus to human cells and produce copies of the SARS-CoV-2 protein, potentially priming immune cells to fight infection. The vaccine is being tested as a single dose and can be stored refrigerated for at least three months, potentially alleviating some of the concerns about the logistics of distribution.
  • Moderna vaccine – Messenger RNA, genetic material carrying information about a viral protein, is delivered to cells that produce the protein, which the immune system is then trained to recognize. RNA vaccines are a newer technology, favored for their potential speed in development, but none have been approved for humans for any virus. The vaccine is being given in two doses and is stored frozen.
  • Pfizer vaccine – This vaccine is also an mRNA vaccine being tested as two doses. It currently requires storage at -70°C (-94°F). Pfizer has an initial agreement with the U.S. government for 100 million doses if the vaccine is approved, with an option for 500 million more doses.
  • AstraZeneca/Oxford University vaccine – Similar to the Johnson & Johnson vaccine, this candidate is a viral vector vaccine but uses a different adenovirus. The vaccine’s trial in the U.S. is currently paused after a “suspected adverse event” in a participant in a U.K. trial of the vaccine. It is being given in two doses and is expected to require refrigeration.

Amidst growing public skepticism and distrust of vaccines, the FDA is planning to tighten requirements for assessing a vaccine’s safety and effectiveness, the Washington Post reported.