How effective is the Johnson & Johnson vaccine against the Delta variant — and do you need a booster shot?

As the more contagious Delta strain continues to surge around the country, vaccine manufacture Johnson & Johnson published new data detailing how efficiently its one-shot dose performs against it.

Their findings — one dose is 79% effective at preventing the Delta variant and 81% effective at preventing severe manifestations of COVID-19 — are similar to vaccines from other companies.

Vaccines aren’t meant to eradicate COVID-19 but to make the condition more manageable for patients, health systems, and commercial markets.

“On Sept. 21, 2021, Johnson & Johnson announced the results of a large, real-world Phase 3 clinical trial of its COVID-19 vaccine,” said Maureen Ferran, a virologist at the Rochester Institute of Technology. “This study collected data from March 1, 2020, through July 31, 2021, and found that the effectiveness of the vaccine did not diminish over the duration of the study, even after the Delta variant became dominant in the U.S.”

The study included 390,000 people who received the Johnson & Johnson COVID-19 vaccine matched on age, sex, and region.

Immunization wanes at a comparable rate to other vaccines

Johnson & Johnson’s one-dose vaccine was shown to continue to produce some level of antibodies for at least six months after vaccination in the participants involved in their analysis. This result is similar to that of patients who received Pfizer and Moderna’s vaccines.

It should be noted that a decrease in antibodies does not, as a rule, correlate with a diminished degree of protection. An antibody count is just one of many factors that determine a body’s level of defense. T-cell count, age, and medical history are also important.

Do you need booster shots?

“In addition to the results of the single–shot study, on Sept 21, 2021, Johnson & Johnson released data about booster shots. The trial gave people a second dose of the Johnson & Johnson vaccine either two or six months after the first dose. In both cases, it increased people’s defense against COVID–19.” Maureen Ferran, a virologist at the Rochester Institute of Technology,  said.

Participants who received a Johnson & Johnson booster shot two months after their initial dose were found to be 94% protected against developing moderate to severe COVID-19, and the number of antibodies present in their blood increased four-fold.

However, those who received a Johnson & Johnson booster shot six months after their first shot increased the number of antibodies in their blood 12-fold, in addition to exhibiting the 94% level of protection associated with the two-month booster.

All of the participants were assessed one month after receiving their booster shots.

“These findings suggest that although a single dose of the Johnson & Johnson vaccine provides strong, durable protection, people may still benefit from a booster because it improves the vaccine’s efficacy,” Ferran concluded.

Booster shots of the Johnson & Johnson and Moderna vaccines are not yet approved (Pfizer has been approved by the FDA). Infectious disease expert Dr. Anthony Fauci said that the FDA may review booster data for the Johnson & Johnson vaccine within a few weeks.

Are there any major side effects?

The vast majority of vaccines — including the Johnson & Johnson and mRNA COVID-19 vaccines — are linked to the same side effects. The bulk of these are similar to those of a severe common cold or a mild version of COVID-19 infection.

The patients involved in the new study reported the following effects:

• injection site reactions: pain, redness of the skin, and swelling.
• general side effects: headache, feeling very tired, muscle aches, nausea, fever.
• swollen lymph nodes.
• unusual feeling in the skin (such as tingling or a crawling feeling) (paresthesia), decreased feeling or sensitivity, especially in the skin (hypoesthesia).
• persistent ringing in the ears (tinnitus).
• diarrhea, vomiting.

More on COVID-19:

• Moderna CEO predicts when COVID pandemic will be over — and why
• A new COVID-19 booster may protect against multiple variants
• Does natural immunity provide a better defense than vaccines?