London, Jan 24 (IANS): People who have received Covid-19 jabs could still pass the virus on to others, UK's Deputy Chief Medical Officer Jonathan Van-Tam has warned.

According to Van-Tam, people should still continue following lockdown rules.

Van-Tam stressed that scientists "do not yet know the impact of the vaccine on transmission". He said vaccines offer "hope" but infection rates must come down quickly, BBC reported on Sunday.

"Even after you have had both doses of the vaccine, you may still give Covid-19 to someone else and the chains of transmission will then continue," he said.

The expert also said that "no vaccine has ever been" 100 per cent effective, so there is no guaranteed protection.

It is possible to contract the virus in the two- to three-week period after receiving a jab, he said -- and it is "better" to allow "at least three weeks" for an immune response to fully develop in older people, the report said.

The warning comes as the UK registered another high daily death count from the virus of 1,348 this weekend, taking the country's total to 97,329.

As per the report, senior doctors have called on health officials in UK to cut the gap between the first and second doses of the Pfizer-BioNTech vaccine.

The maximum wait was extended from three to 12 weeks in order to get the first jab to more people across the UK.

But the British Medical Association said the policy was "difficult to justify" and the gap should be reduced to six weeks.