Dr KK Aggarwal Research Fund 

With inputs from Dr Monica Vasudev

Small risk of bleeding and clotting disorders after AstraZeneca vaccine

There is a small increased risk of immune thrombocytopenic purpura (ITP) and other bleeding and vascular events associated with the Oxford/AstraZeneca vaccine, as per a nationwide analysis of over 2.5 million Scottish adults published in the journal Nature Medicine. These participants had received a first dose of the Oxford/AstraZeneca or Pfizer/BioNTech vaccine between December 2020 and April 2021.

• Oxford/AstraZeneca was associated with a slightly increased risk of ITP up to 27 days after vaccination. 
• The estimated frequency was 1.13 cases per 100,000 first-dose vaccinations.
• Those at greatest risk of ITP tended to be older (median age, ≥69 years old) and had at least one underlying chronic health problem, such as coronary heart disease, diabetes, or chronic kidney disease.
• A very small increased risk of other arterial blood clot and bleeding events associated with Oxford/AstraZeneca up to 27 days after vaccination was also seen. However, there were insufficient data to conclude that there was an association between Oxford/AstraZeneca and cerebral venous sinus thrombosis.

However, the research suggests that the risks are comparable with those seen with other vaccines, including vaccines against hepatitis B, measles, mumps and rubella and influenza.

There was no evidence of an increased risk of the adverse events studied associated with the Pfizer/BioNTech vaccine.

(Source: Dawn OShea. Scottish study estimates risk of bleeding and clotting disorders after AstraZeneca vaccine - Medscape - Jun 09, 2021)

Patients with migraine have higher Covid incidence

A cross-sectional study from the United States has reported higher incidence of Covid-19 as well as heightened COVID symptoms in people who suffer migraines. The study was presented at the American Headache Society virtual meeting.

The study included 66,585 participants, aged 18 to 65 years, in the National Health and Wellness Survey (NHWS); 77% of the respondents were female. Of these, 7,759 people had a migraine diagnosis, while 58,827 did not have migraine. Overall, 3.82% of migraine patients self-reported having COVID-19 and 1.32% said they had tested positive for COVID. In contrast, 2.42% of the group without migraine self-reported having COVID and 0.82% of that group said they had tested positive (all P<0.001). Among those with Covid-19, those who had migraine reported more and higher percentages of COVID symptoms. They also were less likely to use healthcare resources if they tested positive for COVID.

Robert Shapiro, MD, PhD, of the University of Vermont in Burlington said, “Headache is a prevalent symptom of COVID-19, of long COVID, and of post-vaccination for COVID-19. Among COVID-19 inpatients, headache is associated with a positive prognosis. IL-6 levels are lower across the disease course. Headache is associated with 1 week shorter disease course overall. And if someone is admitted with COVID with a symptom of headache, it confers positive relative risk of survival of 2.2.”

(Source: Medpage Today, June 9, 2021)

CVST risk still higher with COVID-19 than with AZ/ J&J vaccination

Rates of cerebral venous sinus thrombosis (CVST) are much higher among patients with Covid-19 compared to persons who have been vaccinated with either the AstraZeneca or the Johnson & Johnson (J&J) vaccine, suggests a study published in the Journal of the American College of Cardiology on June 8.

The rate of CVST associated with the two vaccines was estimated based on the publicly reported data, which was compared to the rate observed among patients hospitalized with Covid-19 and in comparison with the estimated incidence rates among the US population before the pandemic. Data from the United Kingdom Medicines and Healthcare products regulatory agency and the US Centers CDC was used to report the number of events per vaccinated people with the AstraZeneca and Johnson & Johnson vaccines, respectively.

The SVIN COVID-19 multinational study of cerebrovascular events was used to find CVST rates among patients hospitalized with COVID-19. Latest available data from the Nationwide Inpatient Sample database from March and April 2018 were used to report the weighted monthly incidence of CVST before the pandemic.

• Results showed that as of April 14, 2021, there were 77 CVST cases among 21,200,000 AstraZeneca vaccine recipients reported by the UK Medicines and Healthcare Products Regulatory Agency (3.6 per million; 99% CI, 2.7 – 4.8 per million).
• As of April 13, 2021, the Centers for Disease Control and Prevention reported six cases of CVST among 6.85 million vaccinated people (0.9 per million; 99% CI, 0.2 – 2.3 per million).
• In the SVIN COVID-19 registry, 3 of 14,483 patients hospitalized with COVID-19 had CVST (207.1 per million; 99% CI, 23.3 – 757.7 per million).
• In the Nationwide Inpatient Sample, the weighted average rate of CVST in the US population for March and April 2018 was 2.4 per million (99% CI, 2.1 – 2.6 per million).

The authors conclude: “CVST is rare in the general population and after adenovirus-based SARS-CoV-2 vaccination, but appears to be several-fold more common in hospitalized patients with COVID-19.

Additional research is required to fully elucidate the event rates, to understand the risk factors for vaccine-associated CVST and to identify strategies to prevent it. In the meantime, transparent realistic communication of the risk estimates will be helpful for shared decision making between patients and clinicians.”

(Source: CVST risk still higher with COVID-19 than with AZ, J&J vaccination - Medscape - Jun 10, 2021)