FILE PHOTO: A healthcare worker administers a dose of the Sputnik V coronavirus disease (COVID-19) vaccine to her colleague in Podgorica, Montenegro, February 22, 2021. REUTERS/Stevo Vasiljevic/File Photo
ZURICH (Reuters) - Vaccines from AstraZeneca, Russia's Gamaleya Institute and Johnson & Johnson fight the coronavirus with another virus, leaving scientists concerned the shots may lose potency if annual inoculations become necessary to fight new variants. So-called viral vector shots - also used by several Chinese COVID-19 vaccine developers - use harmless modified viruses as vehicles, or vectors, to carry genetic information that helps the body build immunity against future infections. However, there is a risk that the body also develops immunity to the vector itself, recognising it as an intruder and trying to destroy it.
Most vector-vaccine developers have opted to use an adenovirus, a harmless class of common-cold viruses."The experience with adenoviruses has been for many years that vectors can be intercepted by the immune system after repeat injections," said Bodo Plachter, deputy director of the Institute of Virology at Mainz University's teaching hospital.
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