All under-40s are to be offered an alternative to the AstraZeneca vaccine where possible in a precautionary move.

The Joint Committee on Vaccination and Immunisation (JCVI) has reviewed the latest evidence, including the current Covid-19 infection rate, the scale and pace of the vaccine programme and modelling of any third wave.

This has been considered alongside the latest advice from the Medicines and Healthcare products Regulatory Agency (MHRA) on extremely rare cases of concurrent thrombosis (blood clots) and thrombocytopenia (low platelet count) following the first dose of the Oxford/AstraZeneca vaccine.

Professor Wei Shen Lim, Covid-19 chair for JCVI, said: “We have continued to assess the benefit-risk balance of Covid-19 vaccines in light of UK infection rates and the latest information from the MHRA on the extremely rare event of blood clots and low platelet counts following vaccination.

“As Covid-19 rates continue to come under control, we are advising that adults aged 18–39 years with no underlying health conditions are offered an alternative to the Oxford/AstraZeneca vaccine, if available and if it does not cause delays in having the vaccine. The advice is specific to circumstances in the UK at this time and maximises use of the wide portfolio of vaccines available.”

He added: “The Covid-19 vaccines have already saved thousands of lives and the benefit for the majority of the population is clear – if you are offered the vaccine, you should take it.”

This follows the decision on April 7 to offer alternatives to adults under 30. The JCVI added that adverse events following the Oxford/AstraZeneca vaccine are “extremely rare and, for the vast majority of people, the benefits of this vaccine in preventing serious illness and death far outweigh any risks”.

Up to April 28, the MHRA had received 242 reports of blood clots accompanied by low blood platelet count in the UK, all in people who had AstraZeneca, out of around 28.5 million doses given.

These clots occurred in 141 women and 100 men aged from 18 to 93, and the overall case death rate was 20%, with 49 deaths. Six cases have been reported after a second dose of the vaccine.

A particular type of brain blood clot – cerebral venous sinus thrombosis (CVST) – was reported in 93 cases (with an average age of 47), and 149 had other major thromboembolic events (average age 55) accompanied by low blood platelet count.

As a precautionary measure, anyone who has the following symptoms from around four days to four weeks after vaccination is advised to seek prompt medical advice:

• a severe headache that is not relieved with painkillers or is getting worse;
• a headache that feels worse when you lie down or bend over;
• a headache that is unusual for you and occurs with blurred vision, feeling or being sick, problems speaking, weakness, drowsiness or seizures;
• a rash that looks like small bruises or bleeding under the skin;
• shortness of breath, chest pain, leg swelling or persistent abdominal pain.