At least seven cases of Guillain-Barre syndrome – a rare neurological disorder – have been detected by the doctors in Kerala within a month among 12 lakh people who received the Covishield vaccine, prompting them to alert others to watch out for GBS among the vaccine recipients.
“Overall, our experience should prompt all physicians to be vigilant in recognising GBS in patients who have received the ChAdOx1-S vaccine (Covishield in India). While the risk per patient (5.8 per million) may be relatively low, our observations suggest that this clinically distinct GBS variant is more severe than usual and may require mechanical ventilation,” they reported in the Annals of Neurology.
GBS is a rare condition in which the immune system attacks the nerves. The symptoms start as weakness and tingling in the feet and legs. The sensations can quickly spread to the upper body, leading to paralysis in the worst cases.
While the condition may be triggered by an acute bacterial or viral infection, there are treatments available to deal with such medical emergencies.
Out of the seven patients detected by the Kerala doctors, six are women and all of them are 50-70 years of age. They are from Ernakulam, Kottayam and Kannur districts of Kerala where approximately 1.2 million individuals had received the Covishield vaccine as of April 22.
“GBS following vaccination is a rare adverse effect that is likely to be causal. All the seven patients are alive and getting better with treatment,” Boby V Maramattom, the corresponding author of the study and a senior doctor at the department of neurology, Aster Medcity at Kochi said.
The incidence of GBS in India is approximately 6–40 cases per million per year, with a seasonal variation, peaking in the rainy season.
With a denominator of 1.2 million people, the expected cases of GBS per year are approximately seven to 48 annually or between 0.58 to four cases in every four weeks. The reporting of seven GBS cases in 1.2 million people within four weeks (mid March to mid April) marks a 1.4-to-10 fold rise in the incidence of GBS.
“Although the (causative) factors are not completely established, molecular mimicry between viral proteins and human nerve proteins are likely to be a reason,” he said. “It is not completely unexpected with a vaccination but the risk is approximately less than five per million doses.”
A separate team of researchers also reported four such cases from Nottingham in England, an area in which approximately 7,00,000 people received the same vaccine. The frequency of GBS in both the areas was estimated to be up to 10 times greater than expected.
"If the link is causal it could be due to a cross-reactive immune response to the SARS-CoV-2 spike protein and components of the peripheral immune system. The clinicians should be vigilant in looking for this rare neurological syndrome following the administration of Covid-19 vaccines," wrote the authors of the UK report.