Janssen COVID-19 vaccine
The Janssen COVID‑19 vaccine, sold under the brand name Jcovden,[1] is a COVID‑19 vaccine that was developed by Janssen Vaccines in Leiden, Netherlands,[25] and its Belgian parent company Janssen Pharmaceuticals,[26] a subsidiary of American company Johnson & Johnson.[27][28][29]
"Johnson & Johnson vaccine" and "Johnson & Johnson COVID-19 vaccine" redirect here. For other J&J corporate vaccination topics, see Janssen Vaccines, Janssen Pharmaceuticals, and Johnson & Johnson.Vaccine description
It is a viral vector vaccine based on a human adenovirus that has been modified to contain the gene for making the spike protein of the SARS-CoV-2 virus that causes COVID‑19.[5] The body's immune system responds to this spike protein to produce antibodies.[30] The vaccine requires only one dose and does not need to be stored frozen.[31][32]
Clinical trials for the vaccine were started in June 2020, with phase III involving around 43,000 people.[33] In January 2021, Janssen announced that 28 days after a completed vaccination, the vaccine was 66% effective in a one-dose regimen in preventing symptomatic COVID‑19, with an 85% efficacy in preventing severe COVID‑19[34][35][36] and 100% efficacy in preventing hospitalization or death caused by the disease.[37]
The vaccine has been granted an emergency use authorization (EUA) by the US Food and Drug Administration (FDA)[38][39][31] and a conditional marketing authorization by the European Medicines Agency (EMA)[1][40][41] and the UK Medicines and Healthcare products Regulatory Agency.[18] In June 2023, the FDA revoked the emergency use authorization for the Janssen COVID-19 vaccine at the request of its manufacturer.[21][22]
Because cases of thrombosis with thrombocytopenia syndrome and Guillain-Barré syndrome have been reported after receipt of the Janssen COVID‑19 vaccine, the US Centers for Disease Control and Prevention (CDC) recommends "preferential use of mRNA COVID‑19 vaccines over the Janssen COVID‑19 vaccine, including both primary and booster doses administered to prevent COVID‑19, for all persons aged 18 years of age and older. The Janssen COVID‑19 vaccine may be considered in some situations, including for persons with a contraindication to receipt of mRNA COVID‑19 vaccines."[42] In February 2022, Johnson & Johnson announced it has temporarily suspended production of the vaccine though they also noted that it will likely resume at some point in the future and that it will honor all pre-existing contracts that oblige Janssen to supply its vaccine by using the millions of already existing vaccine doses in its inventory where requested.[43]
Pharmacology[edit]
The vaccine consists of a replication-incompetent recombinant adenovirus type 26 (Ad26) viral vector expressing the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein in a stabilized conformation.[2][54] The PER.C6 cell line derived from human embryonic retinal cells is used in the production (replication) of the Ad26 adenovirus vector.[55] It is similar to the approach used by the Oxford–AstraZeneca COVID-19 vaccine and the Russian Sputnik V COVID-19 vaccine[56][57] which use human embryonic kidney (HEK) 293 cells for adenovirus vector replication.[58][59]
The Ad26 viral vector lacks the E1 gene required for replication. Therefore, it cannot replicate in the human organism.[60][61]
Chemistry[edit]
The vaccine contains the following excipients: citric acid monohydrate, trisodium citrate dihydrate, ethanol (alcohol), 2-hydroxypropyl-β-cyclodextrin (HBCD)[62] (hydroxypropyl betadex), polysorbate 80, sodium chloride, sodium hydroxide, and hydrochloric acid.[37][54]
Adverse effects[edit]
Review of Vaccine Adverse Events Reporting System (VAERS) safety monitoring data by the US Centers for Disease Control and Prevention (CDC) through 21 April 2021, (by which time 7.98 million doses of the Janssen COVID‑19 vaccine had been administered), showed that "97% of reported reactions after vaccine receipt were nonserious, consistent with preauthorization clinical trials data."[83]
The most common side effects of the vaccine in the trials were usually mild or moderate, occurred within two days after vaccination, and got better within 1 or 2 days.[84][1][85]
The most common side effects are pain at the injection site, headache, tiredness, muscle pain, and nausea, affecting more than 1 in 10 people. Coughing, joint pain, fever, chills, redness, and swelling at the injection site occurred in less than 1 in 10 people.[1] Sneezing, tremor, throat pain, rash, sweating, muscle weakness, pain in the arms and legs, backache, weakness, and feeling generally unwell occurred in less than 1 in 100 people.[1] Rare side effects (that occurred in less than 1 in 1,000 people) are hypersensitivity (allergy) and itchy rash.[1]
An increased risk of the rare and potentially fatal thrombosis with thrombocytopenia syndrome (TTS) has been associated with mainly younger female recipients of the vaccine.[31][86] This syndrome, marked by formation of blood clots in the blood vessels in combination with low levels of blood platelets 4–28 days after the vaccines administration, occurred at a rate of about 7 per 1 million vaccinated women aged 18–49 years old and it occurs more rarely in other populations (i.e., women 50 years and older and men of all ages).[87]
Allergic reactions, including anaphylaxis, can occur in rare cases within a few minutes to one hour after receiving a dose.[1][88]
In May 2021, with 7.98 million doses administered, the CDC reported four cases of anaphylaxis after vaccination (none of which resulted in death) and 28 cases of cerebral venous sinus thrombosis (of which three resulted in death).[83]
In July 2021, the US fact sheet for the vaccine was updated to indicate that there may be an increased risk of Guillain-Barré syndrome during the 42 days following vaccination.[31][89][90] The European Medicines Agency (EMA) listed Guillain-Barré syndrome (GBS) as a very rare side effect of COVID‑19 Vaccine Janssen and added a warning in the product information.[91]
In August 2021, the Pharmacovigilance Risk Assessment Committee (PRAC) recommended updating the product information to the European Medicines Agency (EMA) that "cases of dizziness and tinnitus (ringing or other noises in one or both ears) are linked to the administration of COVID‑19 vaccine Janssen."[92] Tinnitus was later labeled as "very rare" in a final safety study by the manufacturer.[93]
In December 2021, the CDC accepted the recommendation from a panel of experts for a preference of using the Pfizer-BioNech and Moderna vaccines over the Janssen vaccine due to rare but serious blood clotting events.[94] In May 2022, the FDA limited the use of the Janssen vaccine to those over eighteen unable to access other vaccines or who are otherwise "medically ineligible" for other vaccine options.[95][96]