The mRNA Vaccines Are Looking Better and Better
A year ago, when the United States decided to go big on vaccines, it bet on nearly every horse, investing in a spectrum of technologies. The safest bets, in a way, repurposed the technology behind existing vaccines, such as protein-based ones for tetanus or hepatitis B. The medium bets were on vaccines made by Johnson & Johnson and AstraZeneca, which use adenovirus vectors, a technology that had been tested before but not deployed on a large scale. The long shots were based on the use of mRNA, the newest and most unproven technology.
The protein-based vaccines have moved too slowly to matter so far. J&J’s and AstraZeneca’s vaccines are effective at preventing COVID-19—but a small number of recipients have developed that appears to be linked to the adenovirus technology and may ultimately limit those shots’ use. Meanwhile, with more than
