Here are five updates on the COVID-19 vaccine over the past week:
1. Scientists from the FDA and the National Institutes of Health are advising against one-dose regimens for Pfizer and Moderna's COVID-19 vaccines, saying there is not available evidence to prove a single dose offers long-term protection.
2. The world needs as many as 10 billion syringes for COVID-19 vaccines, and officials in the U.S. say they currently don't have enough, according to a March 5 report.
3. Drugmakers are exploring ways to deliver vaccines without a needle by investigating new delivery methods such as patches, dissolving implants, electrical-pulse systems, nasal sprays and pills.
4. Novartis said March 4 that it will help manufacture CureVac's COVID-19 vaccine candidate. Merck, one of the world's largest vaccine-makers, will work with Johnson & Johnson to boost supply of its single-shot vaccine.
5. President Joe Biden said March 2 that the U.S. is now expected to have enough COVID-19 vaccine doses for all adults by the end of May.