Those Covid-19 vaccines thus far approved by the US FDA have a common feature: they require two shots. The full effectiveness of the Pfizer vaccine requires a second shot three weeks after the first. In the case of the Moderna vaccine, the waiting period is four weeks. This has created an unwelcome complexity for distribution plans. There is now a vaccine on the horizon, from Johnson & Johnson, that might provide the same benefit with just a single shot.
The JNJ vaccine, Ad26.COV2.S, is said to generate strong neutralizing antibodies, with that one shot, in more than 90% of clinical trial volunteers.
JNJ (working especially through its Belgian division, Janssen Pharmaceutica,) has taken an approach different from Pfizer or Moderna. While those companies stored the critical material in single-strand RNA; JNJ’s approach uses double-strand DNA. In both cases, the genetic material is supposed to instruct the host body’s immune system on how it can create antibodies that will break the spikes on the outside of the virus that causes Covid-19, formally called SARS-CoV-2.
The Thing to Know:
The new vaccine is not yet ready for public use. The final stage of testing (phase three) is yet to come. But the idea of a one-shot system is tantalizing.