Vaccines that protect against severe illness, death and long-lasting symptoms of Covid-19 are associated with a small increase in neurological, blood and cardiovascular events, the world’s largest vaccine safety study to date.
The rare events – identified early in the outbreak – included an increased risk of heart-related inflammation in mRNA vaccines made by Pfizer Inc, BioNTech SE and Moderna Inc, and an increased risk of blood clots in the brain after vaccination. Developed by Oxford University and published by AstraZeneca Pvt.
Viral-vector jabs are more likely to develop Guillain-Barré syndrome, a neurological disorder in which the immune system mistakenly attacks the nervous system.
More than 13.5 billion Covid vaccines have been administered worldwide in the last three years, saving more than 1 million lives in Europe alone. Still, quite a few of those who get the vaccine are injured by the shots, sparking debate about their benefits and harms.
The new study, by the Global Immunization Data Network, was published last week in the journal Immunization.
The study looked for 13 medical conditions that the team considered “adverse events of particular interest” among more than 99 million vaccinated individuals in eight countries, hoping to identify more than expected cases after a shot of the Covid-19 virus.
Myocarditis, or inflammation of the heart muscle, was consistently identified following the first, second and third doses of mRNA, the study found.
The greatest increase in the observed-to-expected ratio was observed after the second jab with the Moderna shot. The first and fourth vaccinations are associated with an increase in pericarditis, or inflammation of the thin sac that covers the heart.
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The World Health Organization has declared that Covid-19 is not a global health emergency
The World Health Organization has declared that Covid-19 is not a global health emergency
Researchers found a statistically significant increase in Guillain-Barré syndrome cases within 42 days of the Oxford-developed ChAdOx1 or “Vaxzevria” vaccine that was not seen with the mRNA vaccine.
As a background event, 66 cases were expected – but 190 events were observed.
Experts say that Hong Kong may experience a significant increase in the number of Covid cases in the next 2 months
Experts say that Hong Kong may experience a significant increase in the number of Covid cases in the next 2 months
ChAdOx1 was associated with a threefold increase in cerebral venous sinus thrombosis, a type of blood clot in the brain, identified in 69 events compared to the expected 21.
Low risk has led to discontinuation or restriction of vaccination in Denmark and many other countries. Myocarditis is associated with a third ChAdOx1 level in some but not all people.
After the virus-vector vaccines were identified in the study, possible safety signs for transverse myelitis – inflammation of the spinal cord.
Acute disseminated encephalitis-induced swelling and inflammation in the brain and spinal cord after viral-vector and mRNA vaccines.
Seven cases of acute encephalomyelitis were observed after vaccination with the Pfizer-BioNTech vaccine, compared to two expected cases.
Adverse events of special interest were selected based on vaccine-related interactions, known immune-related factors, and preclinical research. The study did not look at post-orthostatic tachycardia syndrome, or POTS, which some studies have linked to covid vaccines.
Exercise intolerance, extreme fatigue, numbness and “brain fog” were among the common symptoms of more than 240 people with chronic post-vaccination syndrome in a separate study by Yale School of Medicine. The cause of the disease is still unknown and has no diagnostic tests or proven remedies.
The Yale research aims to understand the situation in order to ease the suffering of victims and improve the safety of vaccines, said Harlan Krumholz, the study’s principal investigator and director of the Center for Outcomes Research and Evaluation at Yale New Haven Hospital.
“Both things can be true,” Kruhholz said in an interview. “Millions of lives can be saved, and a small number of people may be negatively affected.”