J&J stated in a statement that an additional dose, either two or six months after the initial shot, can increase protection. Other scientists have not yet reviewed the results or published them.
Because it only requires one shot, the J&J vaccine was seen as an important tool in combating the pandemic. The company was already testing whether a two-dose course would be more effective, even before rollout in the U.S. and other countries. It administered the second dose 56 days after the first.
The two-dose treatment was 75% effective worldwide in preventing moderate to severe COVID-19 and 95% in the U.S., according to the company. This difference is likely to be due to the variants that were being tested in different countries over the course of the long study.
The company found that levels of virus-fighting antibody rose up to four to sixfold when people received a second J&J shot just two months after their first. Six months after the initial J&J shot, a booster dose was administered. This resulted in a 12-fold increase.
The single-dose vaccine is still highly effective. However, Dr. Paul Stoffels, J&J’s chief scientific officer, stated that a booster shot will increase protection against COVID-19. He also said that it would likely extend the protection period significantly.
Data previously released by the company showed that the one-shot vaccine provided protection for as long as eight months following immunization. The company also cited recent data that showed 79% protection against coronavirus infections and 81% protection against COVID-19 hospitalizations in the U.S., even though the extra-contagious Delta variant was spreading.
J&J stated that it provided data to regulators, including the U.S. Food and Drug Administration and the European Medicines Agency to help them make decisions about boosters.
J&J's single-dose vaccine has been approved for use in the U.S.A. and Europe. There are also plans to share at least 200,000,000 doses with the U.N.-backed COVAX initiative, which aims to distribute vaccines to countries in need. However, the company was plagued by production issues and millions of vaccines manufactured in a Baltimore factory were thrown out.
Numerous governments considered using booster shots to combat the spread of the delta variant of the COVID-19 vaccination.
Advisors to FDA recommended that people aged 65 years and over receive a third dose COVID-19 vaccine from Pfizer and German partner BioNTech. The final decision is still pending.
Britain had previously approved booster shots for those over 50 years old and priority groups such as health workers and people with other health conditions. Third vaccine doses have been offered by some countries, including Germany, France, and Israel.
The World Health Organization has asked rich countries to stop giving booster shots until the end of the year. They also suggested that vaccines be immediately redirected to Africa as less than 4% of Africans are fully vaccinated.
In the Lancet journal, top scientists from FDA and WHO argued last week that an average person doesn’t need a booster shot. They also argued that vaccines currently approved provide strong protection against severe COVID-19 and hospitalization.