Extending the gap between two COVID-19 vaccine shots can leave people vulnerable to coronavirus variants, top infectious disease expert of the US, Dr Anthony Fauci said.

Dr Fauci, while talking to NDTV, said, “The ideal interval between doses for mRNA vaccines is three weeks for the Pfizer and four for the Moderna. The problem with extending intervals is that you become vulnerable to variants.”

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He further recommended staying on schedule for vaccination, while explaining that “in the UK, where they extended that interval, in that period you can get infected by the variants.”

The medical advisor to US President Joe Biden was responding to a question about the recommended intervals between two vaccine doses recently revised by the Indian government last month. He also reiterated that the extended gap may be necessary “if you have a very small supply”.

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Last month, Dr Fauci had told news agency ANI that extending the gap between two vaccine doses can be a “reasonable approach” when there is a vaccine shortage.

His remarks had come after the central government revised the interval between two doses of the Covishield (Astrazeneca) vaccine from six-eight weeks to 12-16 weeks. The extended gap of Covishield doses have also been linked to increased efficiency and “better results.”