The soon to be approved vaccine for COVID-19 from Johnson & Johnson requires just one injection, instead of the two required for the previously-approved vaccines from Pfizer and Moderna. The J&J vaccine can be stored with ordinary refrigeration and does not need the extremely cold storage required for the Pfizer or Moderna vaccines.
The J&J vaccine is reported to have an efficacy rate of 66 percent for preventing moderate and severe COVID-19 cases in 43,783 world-wide volunteers. This is less than the 95 percent efficacy rate reported for the Pfizer and Moderna vaccines. However, the J&J vaccine was tested in Africa where a mutated COVID-19 virus is more common and may be more resistant to the vaccines, so the difference in effectiveness may be due to resistant viruses and not due to differences between the vaccines. Flu shots given over many years typically have only up to 50 percent efficacy rates.
The J&J vaccine had an 85 percent rate for preventing severe cases of COVID-19, and none of the vaccinated participants who contracted the disease were hospitalized or died. Of more than 75,000 people who have received one of the vaccines in a research trial, not a single person has died from COVID-19, and only a few people have been hospitalized, none for more than 28 days. Compare that to the fact that of 75,000 people infected with COVID-19, 150 will die and hundreds will be hospitalized. Ordinary flu kills 15 out of every 75,000 infected adults and hospitalizes more than 100 of them.
• The J&J vaccine might be more effective if given as a two-shot vaccine, but it was tested with just one dose. A fourth vaccine, from Novavax, appears to be effective also and approval of this vaccine is expected soon.
• People who have had COVID-19 usually do not need more than one dose of a vaccine. They get extremely high antibody response from just one vaccination (medRxiv, preprint, Feb 1, 2021).