An Overview of the Johnson & Johnson COVID-19 Vaccine

April 23, 2021: The Food and Drug Administration and Centers for Disease Control and Prevention issued a joint statement to lift a pause in the administration of the Johnson & Johnson COVID-19 vaccine after the agencies investigated six reported cases of a rare but severe type of blood clot that occurred within two weeks after individuals received the vaccine. The agencies concluded that the chance of this serious event is very rare and recommended that vaccination resume with added warnings, especially for women under the age of 50.

On February 27, Johnson & Johnson's vaccine against the coronavirus disease 2019 (COVID-19) became the third COVID-19 vaccine to receive emergency use authorization (EUA) from the Food and Drug Administration (FDA).

The company worked with its pharmaceutical arm Janssen to develop the vaccine under the project names Ensemble and Ensemble 2. The company enrolled participants for its late-stage in September, and tested its vaccine with two different doses.

After a single dose was found to be effective in clinical trials, Johnson & Johnson applied for the EUA for the single dose. Now the first COVID-19 vaccine to be given in one dose in the U.S., it's authorized for adults ages 18 and older.

J&J covid

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How It Works

Johnson & Johnson's vaccine is a single-dose adenovirus-based vaccine. It is a viral vector vaccine that uses a weakened live pathogen (adenovirus) as the delivery method (vector) for transporting a recombinant vaccine for COVID-19.

Recombinant vaccines use a small piece of genetic material from the virus to trigger an immune response. This genetic material for COVID-19 does not replicate in the body. A specific piece of the virus can be targeted, and recombinant vaccines are common and generally safe to use in a large population of people—even those with chronic health problems or who are immunocompromised.

There can be some drawbacks to recombinant vaccines. One example is that booster shots may be required over time. Examples of recombinant vaccines are pneumococcal vaccines and vaccines for meningococcal disease.

The science behind recombinant adenoviral vector vaccines has been around for a long time, but the only commercially available adenovirus-based vaccine is a rabies vaccine for animals. Adenovirus-based vaccines may also pose some problems in that the adenovirus is so common that the vaccine may not be as effective once booster doses are given, or that some people may already have immunity to the virus used in the vaccine.

How Effective Is It?

Johnson & Johnson announced that its single-dose vaccine was 66% percent effective at preventing moderate to severe disease from COVID-19 and 85% effective at preventing severe disease. This effectiveness in the Phase 3 trial was reached 28 days after vaccination.

The trial had a temporary delay in October when it paused for an unexplained illness, although no specific details were provided about what happened due to patient privacy. Regulators determined that the event was not related to the vaccine and the trial was safe to resume.

The efficacy against moderate to severe COVID-19 infection varied by region in the trial. It was 72% in the United States, 68% in Latin America, and 64% in South Africa.

The vaccine was also found to be fully protective against hospitalization and death and the protection against severe disease included multiple variants of COVID-19, including the B.1.351 variant found in South Africa.

When Will It Be Available? 

The Johnson & Johnson vaccine was granted emergency use authorization from the FDA for its single-dose vaccine. As of April 28, 2021, Johnson & Johnson (Janssen) has supplied 17.6 million doses to the U.S. and more than 8 million people have received the vaccine, according to the Centers for Disease Control and Prevention (CDC).

In August 2020, Johnson & Johnson announced it had a contract with the U.S. government for 100 million doses (the equivalent of $10 per dose) and the option to purchase an additional 200 million doses. In March 2021, President Biden announced plans to purchase an additional 100 million doses, bringing the total to 200 million doses.

The U.S. government announced a partnership with Merck to help accelerate the production of the Johnson & Johnson vaccine. Merck will receive up to $268.8 million from the Biomedical Advanced Research and Development Authority (BARDA) to adapt and make available its manufacturing facilities for producing the Johnson & Johnson COVID-19 vaccine.

How Much Will a COVID-19 Vaccine Cost?

Any doses purchased by the U.S. government are free to its citizens. While the facility or agency that offers the vaccine may request reimbursement from insurance plans or a public health program for an administration fee, no one can be charged any fees to receive a COVID-19 vaccine or be denied a vaccine if they do not have health insurance.​

Who Can Get the Johnson & Johnson Vaccine?

Everyone 18 and older is now eligible for the Johnson & Johnson vaccine, according to the CDC.

Early vaccine efforts for most COVID-19 vaccine candidates are focusing on adult populations, with vaccine options for children and teens expected later in 2021.

The Johnson & Johnson vaccine is no exception. The vaccine is authorized in adults ages 18 and older, and its Phase 3 trials were conducted in adults aged 18 and up with significant representation of individuals over age 60.

Side Effects and Adverse Events

In every clinical trial, participants are asked to record any reactions they have after receiving a medication or vaccine. Adverse reactions are considered to be medication reactions directly caused by a vaccine, whereas a side effect is a physical reaction to a medication.

Initial safety information released for the vaccine shows that the most common reactions after the vaccine was administered included:

  • Injection site pain, redness, or swelling
  • Fatigue
  • Headache
  • Muscle aches
  • Nausea
  • Fever

People who are immunocompromised, including those receiving immunosuppressant therapies, may have a diminished immune response to the vaccine, according to the FDA.

On April 13, 2021, the FDA and CDC recommended a temporary pause in administration of the Johnson & Johnson COVID-19 vaccine while the agencies investigated six reported cases of a rare but severe type of blood clot that affects the brain called cerebral venous sinus thrombosis (CVST) occurring along with thrombocytopenia (low platelet count), which can make the condition difficult to treat.

In their review the CDC and FDA accounted for nine additional cases of rare blood clots paired with low platelet counts, bringing the total to 15 out of 8 million administered doses. Most cases occurred in women between the ages of 18 to 49 within one to two weeks of vaccination. The agencies concluded that the potential benefits outweigh this very rare risk and lifted the pause after 10 days.

A warning was added to the fact sheets for healthcare providers and vaccine recipients and caregivers about the rare risk of thrombosis in the cerebral venous sinus and other sites (including blood vessels in the abdomen and veins of the lower extremities) along with low platelet counts after receiving the vaccine.

Healthcare providers have also been warned that treating a suspected case of this condition (known as thrombosis with thrombocytopenia) with the blood thinner heparin may be harmful and alternative treatments may be needed along with a consultation with hematology specialists.

Warning Symptoms

Seek emergency medical care if you experience any of the following symptoms:

  • Shortness of breath
  • Chest pain
  • Leg swelling
  • Persistent abdominal pain
  • Severe or persistent headaches
  • Blurred vision
  • Easy bruising or tiny blood spots under the skin (beyond the injection site)

Funding and Development

Johnson & Johnson co-funded the development of the vaccine as part of Operation Warp Speed, a public-private partnership initiated by the U.S. government to facilitate and accelerate the development of a COVID-19 vaccine, manufacturing, and distribution of COVID-19 vaccines, with funding from the Biomedical Advanced Research and Development Authority (BARDA)—a U.S. government program aimed at furthering the manufacture and distribution of vaccines to fight COVID-19. Johnson & Johnson said $1 billion has been invested in the vaccine project by both the company and BARDA.

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  11. Johnson & Johnson. Vaccine candidate for COVID-19; landmark new partnership with U.S. Department of Health & Human Services; and commitment to supply one billion vaccines worldwide for emergency pandemic use. Updated March 30, 2020.