News

Local study on AstraZeneca Covishield: 1st dose protection drops after 4 months

  • Major drop in antibodies
  • Result the same across all ages 
  • 26.1% had no antibodies 
  • Giving 2nd jab soon is the answer 

BY Pamodi Waravita 

A study conducted on the immune responses of 553 Sri Lankans to a single dose of the Oxford AstraZeneca Covishield vaccine after 16 weeks post-vaccination has found that neutralising antibodies against the Covid-19 virus have significantly reduced across all age groups. 

The Covishield vaccine is manufactured by the Serum Institute of India.

“Our findings showed that 26.1% of the participants did not have neutralising antibodies by 16 weeks (post-vaccination). Neutralising antibodies, which are a proportion of all antibodies, are the parameters of protection against the virus. They basically show how protected one is and are the most important for one’s protection,” the University of Sri Jayewardenepura (USJ) Allergy, Immunology, and Cell Biology Unit Director, and a researcher involved in said study Dr. Chandima Jeewandara told The Morning yesterday (29). 

Dr. Jeewandara further said that antibodies to Variants of Concerns (VOCs) of the virus were not detected, or were very low in all individuals after 16 weeks of receiving the first dose of the Covishield vaccine. 

The World Health Organisation (WHO) has classified VOCs as having an increase in transmissibility, creating a detrimental change in the Covid-19 epidemiology, an increase in virulence, a change in the clinical disease presentation, or causing a decrease in the effectiveness of public health and social responses to the virus such as vaccines. 

“However, the participants in the study had very good memory T and B cells (lymphocytes/white blood cells that are part of the immune response system) responses, and therefore, administering a second dose as soon as possible would definitely boost the immune responses,” added Dr. Jeewandara.

As of 28 July, the Epidemiology Unit stated that 925,242 individuals have received the first dose of the Covishield vaccine by April 2021, with some receiving it as early as 29 January. 

However, only 385,885 of them have received their second dose. Although the authorities have been assuring the public that the required stock of the Oxford AstraZeneca vaccine would reach the country by this month, they are yet to arrive. The Production, Supply, and Regulation of Pharmaceuticals State Ministry has confirmed a statement made by Health Minister Pavithra Wanniarachchi saying that these Oxford AstraZeneca vaccines manufactured by Japan would arrive in the country tomorrow (31).