COVID-19 vaccine breakthrough infections—what we know and what we don’t

Vaccine effectiveness drops to 52 per cent against Omicron around six months after taking the second vaccine shot | Image - Eunice Dhivya

The COVID-19 pandemic and its impact globally has seen accelerated research and development of vaccines at a pace previously unheard of. This has resulted in a number of vaccine candidates being developed and approved by respective regulatory agencies in different countries for use on humans.

Countries across the world have secured and authorised one or more of the many COVID-19 vaccines. They could be either mRNA or DNA vaccines, adenovirus backbone vaccines or protein subunit vaccines. Active vaccination of global populations, starting with healthcare workers, commenced in many countries early this year.  Early results suggest that......