Anthony Fauci, the top infectious medicine expert in the United States, said Covid-19 vaccine boosting injections should be provided "reasonably as soon as possible" to people with weakened immune systems.。

Fauci's remarks come amid a growing debate about "breakthrough" infections among people who have been fully vaccinated, and opinions vary as to whether strengthening needles should be approved. Israel became the first country to provide reinforcement needles widely on Sunday, saying it had given more than 420,000 doses of strengthening needles to people aged 60 and over.

Fauci says most people with impaired immune systems, including those who have received organ transplants or are undergoing chemotherapy, do not get enough immune response from the Covid-19 vaccine.

As for whether other people should be vaccinated with booster shots, Fauci said that once the CDC sees clear evidence in the data, it will give such advice "as soon as possible".