We have it! A vaccine that’s easy to store, has an expansive shelf life, has minimal side effects, and stops the pandemic cold. No more spreading. No more illness. No more loved ones lost. IF ONLY…! But there is great hope that one of the three currently available vaccines will do just that.
On Feb. 27, the Food and Drug Administration announced it had issued an emergency use authorization for Johnson & Johnson’s one-dose Covid vaccine. Developed by J&J’s vaccines division, Janssen Pharmaceuticals, it was shown to be 66% protective against moderate to severe Covid infection in a multi-country study. Importantly, it was 85% effective in protecting against severe disease.
A new variant appears to resist the immunity induced both by infection and by Covid vaccines, which were designed to target earlier strains of the SARS-CoV-2 virus. Overall efficacy has varied geographically, particularly in South Africa,
Rollout of the vaccine has already started, though the company is not expected to be able to supply ample numbers of doses until April.
The Pfizer and Moderna vaccines are made using messenger RNA, or mRNA, a technology that delivers a bit of genetic code to cells — in effect, a recipe to make the surface protein (known as spike) on the SARS-2 virus. The proteins made with the mRNA instructions activate the immune system, teaching it to see the spike protein as foreign and develop antibodies and other immunity weapons with which to fight it.
The J&J vaccine uses a different approach to instruct human cells to make the SARS-2 spike protein, which then results in an immune response. The approach is a viral vectored vaccine. A harmless adenovirus — from a large family of viruses, some of which cause common colds — has been engineered to carry the genetic code for the SARS-2 spike protein. Once the adenovirus enters cells, they use that code to make spike proteins. J&J employed this same approach to make an Ebola vaccine that has been authorized for use by the European Medicines Agency.
The Pfizer vaccine has been authorized for use for people aged 16 and older. Moderna’s has been cleared for use in people 18 and older, though the company is now testing its vaccine in 12- to 17-year-olds. J&J’s vaccine has been tested in people 18 and older, and that’s who it was authorized for. When testing in children and younger teens is done, this vaccine may be available for use to those under 18 years old either.
Vaccine efficacy or the ability to produce a desired or intended result
The Pfizer and Moderna vaccines have been about equivalent in efficacy, in the early stages after vaccination.
The Pfizer vaccine showed efficacy of 95% at preventing symptomatic Covid infection after two doses. The vaccine appeared to be more or less equally protective across age groups and racial and ethnic groups.
The Moderna vaccine was 94.1% effective at preventing symptomatic Covid-19 after the second dose. The vaccine’s efficacy appeared to be slightly lower in people 65 and older, but during a presentation to the Food and Drug Administration’s advisory committee in December, the company explained that the numbers could have been influenced by the fact there were few cases in that age group in the trial. The vaccine appeared to be equally effective across different ethnic and racial groups.
Comparing the efficacy of those vaccines to the efficacy of Johnson & Johnson’s is challenging because of differences in the designs of the Phase 3 clinical tests. The trials were testing for different outcomes. Pfizer’s and Moderna’s trials both tested for any symptomatic Covid infection. Pfizer started counting cases from seven days after receipt of the second dose of vaccine, while Moderna waited until day 14 to start counting cases.
J&J, was assessing whether one dose of its vaccine protected against moderate to severe Covid illness — defined as a combination of a positive test and at least one symptom such as shortness of breath, beginning from 14 or 28 days after the single shot. (The company collected data for both.)
Because of the difference in the trials, making direct comparisons is difficult. Additionally, Pfizer and Moderna’s vaccines were tested before the troubling new variants appeared in Britain, South Africa, and Brazil. Not enough information exists to state how these vaccines are faring against mutated viruses.