What You Must Know About Johnson & Johnson’s Covid-19 Vaccine
The FDA recently authorized the use of the
Johnson & Johnson coronavirus vaccine in adults. As the efforts for
global immunization are being challenged by various logistical issues
and new variants of the virus, this development could provide
much-needed aid.
There is one particular advantage to the
new vaccine. If you experience an allergic reaction to the Moderna or
Pfizer vaccines, the CDC now says you can try Johnson & Johnson as
your second dose. Read on to find out how the new vaccine compares to
the existing ones and when it can be used as a substitute for another
vaccine.
How does the Johnson & Johnson vaccine work?
The Johnson & Johnson vaccine is a viral vector vaccine, which is a
traditional approach to vaccine production. To create this vaccine, the
team took a harmless adenovirus – the viral vector – and replaced a
small piece of its genetic instructions with coronavirus genes for the
SARS-CoV-2 spike protein.
When injected into a person’s arm, it
enters the cells. The immune system then notices these foreign proteins
and makes antibodies that will protect the person if they are ever
exposed to SARS-CoV-2 in the future. In that regard, the Johnson and
Johnson vaccine is similar to the AstraZeneca-Oxford vaccine and the
Russian Sputnik vaccine.
How does Johnson & Johnson compare to
existing vaccines?
The main difference is that Johnson and Johnson is a viral vector
vaccine while the Moderna and Pfizer vaccines both work using a novel
method called mRNA. Messenger RNA vaccines use genetic instructions from
the coronavirus to tell a person’s cells to make antibodies to the
spike protein, but these don’t use another virus as a vector.
There are quite a few practical differences that stem from these
different approaches:
1. Both of the existing mRNA vaccines require two shots, while Johnson
& Johnson only requires one dose. This is crucial when vaccines are
in short supply.
2. The Johnson & Jonson vaccine can be stored at much warmer
temperatures than mRNA vaccines, which need to be shipped and stored at
below-freezing temperatures. The Johnson & Johnson vaccine, on the
other hand, can be stored for at least three months in a regular
refrigerator, making it much easier to use and distribute.
3. As for efficacy, the Jonson & Johnson vaccine was found to be 72%
effective at preventing COVID-19 and 86% effective at preventing severe
cases of the disease. While there is still a chance a vaccinated person
could get sick, their risk of hospitalization or death from COVID-19
would still be much lower. The FDA report also indicates that the
vaccine protects from the UK and Brazil variants. As for the South
African variant, researchers found the new vaccine less effective at 64%
overall, but the vaccine was still 82% effective at preventing severe
disease.
While Pfizer and Moderna are reported to be approximately 95% effective
at preventing Covid-19, experts note that it’s difficult to directly
compare the Johnson & Johnson jab to the mRNA vaccines due to the
differences in how the clinical trials were designed.
The Johnson & Johnson trials were done more recently than the
others, and they took into account the vaccine’s efficacy against the
new variants as well.
The use of the Johnson & Johnson
vaccine in people allergic to mRNA vaccines
In general, health officials recommend that you get the same vaccine
twice because it's difficult to assess how effective and safe mixing two
vaccines is. However, if you experience an allergic reaction to the
first dose of the Moderna or Pfizer vaccine, it is still possible for
you to get vaccinated against the novel coronavirus with the Johnson
& Johnson (or Janssen) vaccine, according to Jessica MacNeil, MPH,
an epidemiologist at the CDC’s National Center for Immunization and
Respiratory Diseases. MacNeil further added that this could only be done
under the supervision of a healthcare provider.
An immediate allergic reaction occurs
within the first 4 hours after the vaccination. It is considered severe
“when a person needs to be treated with epinephrine, or EpiPen, or if
they must go to the hospital," states the CDC.
It’s important to note that allergic reactions after the coronavirus
vaccine are rare - only 2-5 people per million vaccinated in the US have
experienced anaphylaxis after getting their shot. So while these new
guidelines may certainly help some, the vast majority of the population
won’t need to consider them.
All things considered, having multiple vaccines against Covid-19 is
important, and the authorization of the Johnson & Johnson vaccine in
the US is a big step towards ending the pandemic.