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Patient monitoring needed to assess effectiveness of Covid vaccine after dosing schedule change, say experts

by Awil Mohamoud
6 January 2021

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A programme of ‘robust’ immune monitoring is needed to assess how altering the Covid-19 vaccine dosing schedule impacts the effectiveness of both available jabs, experts have warned.

This comes after the Government last week announced that healthcare professionals should administer the second Covid vaccination dose 10-12 weeks after the first, rather than after three weeks – as originally planned – in a bid to vaccinate more people sooner. 

The British Society for Immunology (BSI) said that while it would ‘prefer’ the original three-week interval schedule tested during the trial phase to remain, it ‘recognises that a pragmatic approach in the short-term is needed, and accepts the rationale for the change in dosing schedule’.

However, it is also now urging the Government to make a number of assurances – including to monitor the impact of the dosing schedule change on the efficacy of the vaccines.

The statement said: ‘This monitoring should include studies from a number of sources, including the vaccine development teams but also monitoring from Public Health England and the devolved nations to learn as much as we can about how the altered dosing schedule affects immune responses in the medium and longer term. 

‘We have been assured by the Government that this monitoring is in place and will be conducted. The BSI will track progress and advocate for data to be made available for analysis and scrutiny.’

The BSI also called for the Joint Committee on Vaccination and Immunisation (JCVI) to make evidence for decisions around the Covid vaccines available ‘immediately’ after announcements are made, to aid public understanding. 

‘An open and transparent approach is required to build public trust, and thus having access to the evidence and rationale behind the public health decisions taken is important,’ it added. 

It further called for ‘strong and clear’ public messaging from the Government, reiterating that ‘the highest level of protection is only gained through two doses of the vaccine’.

This is necessary, the BSI added, because the longer interval between both Covid vaccine doses could now risk a larger proportion of those receiving a first dose failing to return for the second instalment – thereby ‘compromising the protection levels in the most vulnerable in society’.

‘We have been assured by Government that this is a priority and that the policy is to deliver the second dose with a maximum of 12 weeks,’ it added.

The non-profit organisation also called for an engagement programme with the public to boost understanding and confidence in the Covid vaccines. 

‘Unlikely to have a negative effect’

The chief medical officers (CMOs) said in a statement on 31 December that the new dosing schedule will mean twice as many people can get vaccinated over the next two to three months – though they will have around 70% protection until the second jab. 

Following advice from the JCVI, the statement said that this model is preferred to one where half as many people are vaccinated during this period, but given the highest level of protection.

The BSI said in its statement: ‘There is no current evidence that either of the two approved vaccines can prevent infection by the virus (rather they stop disease), so any concerns that delaying a second dose would have adverse effects on virus transmission remain hypothetical. Close monitoring of the vaccinated population will now be needed in order to garner further evidence.

‘Most immunologists would agree that delaying a second ‘booster’ dose of a protein antigen vaccine (such as the two approved Covid-19 vaccines) by eight weeks would be unlikely to have a negative effect on the overall immune response post-boost. We also would not expect any specific safety issues to arise for the individual due to delaying the second dose, other than an increased potential risk of disease during the extended period due to lowered protection.’