Johnson & Johnson’s single-shot Covid-19 vaccine (JNJ-78436735 or Ad26.COV2.S.)

Subject: Science and Technology

Context: The US FDA on Saturday authorised Johnson & Johnson’s single-shot Covid-19 vaccine for emergency use, third vaccine to reach US citizen.

Concept:

It has been developed by Janssen Pharmaceutica, a Belgium-based division of the company, in collaboration with Beth Israel Deaconess Medical Center.
Currently two-shot vaccines made by Pfizer-BioNTech and Moderna are being given in USA.
Concern over J&J’s single shot vaccine have been raised as it had 72% efficacy rate in the US clinical trial site (other two had 95%).
It is based on the SARS-CoV-2 virus’s genetic instructions for building the spike protein that it uses to enter human cells. But unlike the Pfizer-BioNTech and Moderna vaccines, which store the instructions in single-stranded RNA, the J&J vaccine uses double-stranded DNA.

Significance:

It is adenovirus-based, which is a more rugged type than the mRNA vaccines from Pfizer and Moderna. DNA is not as fragile as RNA, and the adenovirus’s tough protein coat helps protect the genetic material inside. As a result, the J&J vaccine can be refrigerated for up to three months at 2-8°C.
Unlike the Pfizer, Moderna, Oxford-AstraZeneca (Covishield in India), Covaxin which are double dose, this vaccine is single dose.