Vaccine side effects drop significantly during second vaccination drive

Out of the total population – 722,994 – of the country, so far, 66 percent received the second dose and over 72 percent received the first dose

Lhakpa Tshering

In the past two weeks after the second vaccination drive, some 3,850 people reported minor side effects after receiving their second dose of the Covid-19 vaccine. This is a drop of more than twice the earlier figure – with some 9,400 cases – reported during the first national immunization drive.

The reported Adverse Events Following Immunization (AEFI) includes pain and swelling at the site of vaccination, more serious symptoms such as headaches, and fever, allergic reactions have also been reported.

A member of the National Immunization Technical Advisory Group (NITAG), Dr. Guru Prasad Dhakal, said that the decrease could be due to using two different vaccines for the first and second dose. “Our body responds to different vaccines in a different manner,” he said. “This time we offered boosters with the Moderna mRNA vaccine.”

He also added that studies have shown the first dose of Pfizer or Moderna mRNA vaccines would have lesser side effects than the ones experienced after the second shot followed by a booster with the same (homologous) method of vaccination.

Dr. Dhakal said that side effects would be more intense if one takes the second dose of mRNA vaccine in homologous mode. “It is the second dose of mRNA vaccine which will cause more side effects,” he added.

“This time the side effects were fewer, probably because we are taking the first dose of mRNA vaccine because of a heterologous schedule. We assume maybe this first dose did not cause more side effects,” he said.

On the other hand, he said, people must have been more used to the side effects given that they have already experienced some forms of side effects after the first jab. “So when they got the first dose, more people reported but this time they would have felt assured some side effect is expected,” he said.

“They must have been more complacent. But they have the option to self-report the side effects through Bhutan Vaccine System (BVS),” Dr. Dhakal said.

Besides, the decrease is also attributed to the fact that people were provided with paracetamol as prophylaxis during the second vaccination drive.

“This time since they were already given paracetamol, these minor effects such as headache, and body pains, they won’t have reported,” he added. “Rather than reporting, they would have taken the paracetamol and could have stayed back home.”

AEFI cases were mostly reported among females across all age groups as compared to their male counterparts.

In terms of age group, the proportion of AEFI was the highest among the age group of 25 to 34 in both first and second dose with 2.16 percent and 1 percent, respectively, followed by 35 to 44 and 18 to 24 years. The least AEFI was reported among 75 years of age and above with about 2 percent.

Among the special group, five of the 582 pregnant women vaccinated had experienced AEFI. And, less than one percent cases were reported among breastfeeding mothers and people with food and medical allergies.

Thirteen people developed serious AEFI after receiving the second jab that has drastically declined compared to 48 serious AEFI were reported for the first dose. 

Among the serious side effects, only four cases were managed as anaphylaxis compared to 10 cases in the prior vaccination drive. And, two severe allergic reactions, one seizure, and two unrelated deaths have also been reported for the second dose.

Dhakal said that the suspect cases of anaphylaxis were not life-threatening reactions because of the vaccine. “The NITAG will again discuss whether it meets the definition of anaphylaxis or the number may come down after the analysis,” he said.

All vaccinated people were observed for 30 minutes after the vaccination (active AEFI surveillance). If no AEFI is observed or self-reported within the 30-minutes the people were provided with contact details to report the AEFI or they were asked to visit the nearest health center (passive AEFI surveillance).

Side effects or reactions following the vaccination were reported online through BVS to NITAG and regional NITAGs established in Mongar and Gelephu.

The use of the BVS was noted to be instrumental in allowing real-time reporting of AEFIs and the dashboard on AEFIs was found to be very useful for providing a snapshot of the AEFIs reported.

Dhakal said, “Since we have the contact numbers of the patients and the health workers on BVS, we can get the real-time report and give them real-time management from here immediately.”

“Any serious adverse events that are reported, we can follow up with the health workers and follow up with the patients immediately,” he said. “The other thing is even if there are some adverse events which have been seriously and mistakenly reported as minor, we can talk with the patients and health workers and then reclassify it and manage any serious events immediately.”

The establishment of regional NITAG facilitated the monitoring and managing of the AEFIs in their respective region and this enabled better and faster review of AEFIs at the National level by the NITAG.

Bhutan’s AEFI surveillance is noted to be robust compared to many in the region. Given this strong system, it has reported the highest rates of AEFIs in the region after the first vaccination drive.

In the meantime, about 94 percent of people received a heterologous vaccination and a little over 6 percent received a homologous vaccination regimen so far.

The mean age of the people for the second dose of vaccination was 38.6 years and the median age was 37 years (minimum 11 and maximum 106) years.

Out of the total population – 722,994 – of the country, so far, 66 percent received the second dose and over 72 percent received the first dose. And, over 90 percent of eligible adults have been fully vaccinated to achieve herd immunity against coronavirus.