J&J Covid-19 vaccine trial in SA: What early results on safety from the Sisonke study revealed

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  • During the Sisonke Covid-19 trial, nearly 289 000 healthcare workers were vaccinated with the J&J vaccine
  • Five participants developed rare blood clots but they turned out to have known risk factors 
  • The majority of participants had mild to moderate side effects – the safety data were published in a reputable journal this week

As of 12 April 2021, out of 288 368 South African healthcare workers vaccinated with the Johnson & Johnson (J&J) vaccine, 50 had serious side effects that were followed up by researchers. The majority (85%) of participants experienced mild to moderate effects.

Healthcare workers received the vaccine as part of the the country's Sisonke Covid vaccine study. The early safety data was reported in the New England Journal of Medicine on Wednesday.

In their paper, the authors note that no cases of the rare blood clotting condition, known as vaccine-induced immune thrombotic thrombocytopenia (VITT), were detected in the SA study. Around 28 cases have been identified in vaccinated individuals in other countries.

Co-author of the study, Professor Ian Sanne, an infectious diseases specialist and CEO of Right to Care, told Health24 that VITT is a very specific immune-driven occurrence that has been responsible for the temporary pause of the use of the jab in the US, European Union, and South Africa.

"The cause is idiopathic (uncertain origin), but we have not identified a case in the South African study," he said.

Five participants in the Sisonke study, however, developed blood clots but had known risk factors for thromboembolism, a potentially harmful form of blood clotting that moves through the body.

“In South Africa, since the start of the pandemic, Covid-19 has been reported in 1.58 million persons, including more than 55 000 healthcare workers,” the authors wrote. “The rate of adverse events with vaccination is low, and thromboembolic events have occurred mainly in persons with risk factors for thromboembolism.”

SA's status on J&J rollout

According to the J&J clinical trial, in which SA participated, the single-dose vaccine prevented 100% of hospitalisations and deaths related to Covid-19.

There has been a delay in the SA rollout of the J&J vaccine after it was found that there was a lack of adherence to proper standards at a manufacturing plant in the US, News24 reported. The government is expecting an announcement by the US Food and Drug Administration (FDA) on Friday, which may allow for the programme to continue.

Majority of side effects mild to moderate

Professor Linda-Gail Bekker, the co-lead investigator of the Sisonke study, previously told Health24 that the vast majority of side effects from the J&J jab have been mild and short-lived – a point reiterated in the recently published report.

According to the data, the majority (81%) of side effects among participants were mild to moderate. Fifty healthcare workers had serious side effects. Among this group, 12 cases were linked to Covid infection.

Twelve participants also had allergic reactions, of which one met the criteria for anaphylaxis – a severe, potentially life-threatening allergic reaction.

Participants who had experienced allergic reactions had recovered and are doing well, Sanne said.

Bekker previously advised that people who are prone to allergies inform the healthcare personnel who administer vaccines beforehand. This is so that they can be observed and monitored for any allergy-related reactions for around 30 minutes post-vaccination.

“We normally observe people for 15 minutes anyway, regardless of whether they have symptoms or not, but in those that have allergic responses – we want to monitor them for a bit longer. If there is no impact, they can leave just like anybody else,” she said.

Six of the participants had neurologic conditions, including a 40-year-old man who was diagnosed with Guillain-Barre syndrome and a 53-year-old woman with Bell's palsy.

Blood clots in five HCW

Out of the five cases of blood clots in healthcare workers who received the jab, one occurred in a 63-year-old woman who was overweight, had high blood pressure, diabetes, and a history of venous thrombosis (VTE) – a condition in which a blood clot commonly forms in the deep veins of the leg, groin, or arm. This was reported 23 days after vaccination. Sadly, the woman died.

The other four cases of blood clots occurred in women aged 64, 45, 38, and 65.

In total, four of the five cases were linked to the vaccine, while the one case was possibly linked, said Sanne, but he stressed that the four women had underlying disease that put them at risk of developing thromboembolism.

According to Johns Hopkins Medicine, risk factors include having Covid disease; being pregnant; taking birth control pills; being overweight or obese; smoking; and living an inactive lifestyle, among others.

The safety data report highlights that the five cases of blood clots translates to 1.7 events per 100 000 participants. 

"The case rate is there, and that needs to be seen in context," said Sanne. "Around 85% of people who are infected and hospitalised with Covid experience thrombosis, and, unfortunately when post-mortems are done, at least 40% indicates death as a consequence of thrombosis in the lungs or emboli.

"And so, this rate of 1.7 out of 100 000 is infinitely lower than the complications of Covid infection," he said.

Risk is greater from Covid infection

Supporting Sanne's point is a recent analysis from the American Heart Association which noted that the risk of blood clots due to infection with Covid is 8 to 10 times higher than the risk of blood clots after receiving a Covid vaccine, Health24 reported.

The CDC also previously stated that in the US up to 600 000 people a year develop blood clots in their lungs, or leg veins, or other parts of the body, which means that around 1 000 to 2 000 cases of blood clots occur in the population every day.

*For more Covid-19 research, science, and news, click here. You can also sign up for our Daily Dose newsletter here.

READ | What are the blood clots associated with the Johnson & Johnson Covid-19 vaccine? 4 questions answered

READ | Vaccine side effects are not uncommon - so, with J&J's jab: What are they, who gets them, and why?

READ | Covid-19 vaccine blood clot condition can be fixed, German scientists believe

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