Intended for healthcare professionals

CCBY Open access

Rapid response to:

Research

Risk of thrombocytopenia and thromboembolism after covid-19 vaccination and SARS-CoV-2 positive testing: self-controlled case series study

BMJ 2021; 374 doi: https://doi.org/10.1136/bmj.n1931 (Published 27 August 2021) Cite this as: BMJ 2021;374:n1931

Linked Editorial

Strengthening international surveillance of vaccine safety

Rapid Response:

What is the appropriate comparison?

Dear Editor

A patient under 45 with no health conditions receiving the Covid-19 vaccine has a right to know:

(1) If I get vaccinated, what is my risk of hospitalization and death from complications of the vaccine?
(2) If I don't get vaccinated, what is my risk of hospitalization and death from complications of SARS Cov-2 infection that would be prevented by the vaccine?

We need to compare (1) and (2), and we should only advise vaccination if (2) is greater than (1).

This article gives the short-term risk of vaccination (about 1 in 55,000). This under-estimates the risk in (1) because it does not include the long-term risk of the vaccine nor the risk of the second dose.

The risk in (2) is the crude mortality/hospitalization rate from SARS Cov-2 infection minus the risk of serious infection despite the vaccine. The ONS has published crude mortality rates in different age groups for the period before vaccination started. The ONS data over-estimate the risk in (2) because they do not include the risk of infection despite the vaccine, the protective effects of natural immunity and herd immunity, and the lower risk of people without chronic health conditions.

Lisa Shaw proceeded with vaccination in the belief that the risk (2) was greater for her than the risk in (1) but I am no longer convinced that this is the case. I do not feel confident to advise patients under 45 with no health conditions that the vaccine is in their best interests. You can make the case that vaccination is still worthwhile in these patients for the public health benefit, but informed consent is required and the patient needs to be told that they are putting themselves at a small personal risk for the sake of protecting vulnerable people in the population.

Competing interests: No competing interests

31 August 2021
Imran M Usmani
General Practitioner
Southwark CCG