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Current Affairs

Self-replicating mRNA vaccines

Date: 27 April 2022 Tags: Biotechnology


A self-amplifying mRNA vaccine has shown promising results against Covid-19 in trial phases.



In this form of vaccine, the delivered RNA multiplies inside the body.



  • The vaccine is named ARCT-154 and is developed by Arcturus Therapeutics Holdings, based in San Diego, California.

  • The trials are currently going on in Vietnam. It offers 95% protection against severe Covid and death while 55% against Covid infection.


Working of mRNA vaccines

  • In normal mRNA vaccines, a messenger RNA is used to encode the spike protein of the coronavirus.

  • The mRNA asks cells to produce spike protein of the virus so that immune system can recognise the spike and act when actual infection takes place.


Self-amplifying vaccine

  • In this type of mRNA vaccine, four extra proteins are coded in addition to the vaccine antigen. The original RNA strand is amplified once inside cell.



  • Two-dose human trials demonstrated 55% vaccine efficacy for protection against Covid-19.

  • The efficacy against severe Covid and death was reported to be 95%.


Adverse health effects

  • No cases of myocarditis or pericarditis were observed.

  • Majority of solicited adverse events were mild or moderate in severity.



  • The most basic advantage is the lower dosage required.

  • The vaccine will be easier to store, and will cost lower due to small dose.