Over the past few months, two vaccines have been rolled out in the U.S. – one manufactured by Moderna, the other by Pfizer. And a third coronavirus vaccine has recently been granted Emergency Use Authorization by the U.S. Food and Drug Administration – the Janssen COVID-19 Vaccine developed by Johnson & Johnson. The federal government is set to start distributing the J&J vaccine almost immediately.
Compared to the other two vaccines, which are designed to be administered in two doses, J&J’s vaccine is a single-dose vaccine, which could result in quicker protection from the virus – just two weeks following inoculation. Moderna and Pfizer’s vaccines requires a second dose to get the full effect of vaccine’s protection against the virus. The second dose is administered three to four weeks after the first shot has been given, taking about five to six weeks total for the vaccine to reach full efficacy.
J&J’s vaccine has a different efficacy rate though, with a 66% efficacy against moderate to severe illness, 85% effective against severe disease compared to the 95% and 94% efficacy rates of Moderna and Pfizer’s vaccines. However, trials have so far shown it to be 100% effective at preventing death from COVID-19.
It’s also made with a different technology – using viral vectors versus the messenger RNA of earlier vaccines. Per the CDC, viral vectors “use a modified version of a different virus (the vector) to deliver important instructions to our cells.” It works by employing the cell’s machinery to generate COVID-19 spike proteins – a harmless piece found on the surface of the virus – which will then trigger the immune system to create antibodies and activate other immune cells to fight off what it thinks is an infection.
On the other hand, mRNAs generate antibodies and immune cells that “remember” what the coronavirus looks like to be able to respond quickly in case of a fresh attack. However, both technologies are similar in the sense that they work by delivering genetic instructions.
The three available vaccines, however, all do not contain additives such as antibiotics, preservatives or adjuvants, a.k.a. compounds used to boost the immune response, as these can sometimes cause strong reactions, hence, there is very low risk of allergic reaction. All three also appear to stimulate an overwhelming immune response — one much stronger than people get after a natural infection.
According to the FDA’s website, the most commonly reported side effects from J&J’s vaccine include “pain at the injection site, headache, fatigue, muscle aches and nausea.” The side effects mostly occur within 1-2 days following vaccination, lasting 1-2 days with mild to moderate in severity.
More vaccines being available is certainly good news – along with the declining number of new cases. However, in order to keep the numbers down and avoid another spike in new cases, health experts still continue to urge everyone to practice more immediate measure to curb the spread of COVID-19 – such as avoiding large indoor gatherings, wearing masks, practicing physical distancing and using other public health measures.
Take care and stay safe, everyone!