Comparison of kinetics of immune responses to SARS-CoV-2 proteins in individuals with varying severity of infection and following a single dose of the AZD1222

  1. Deshni Jayathilaka
  2. Chandima Jeewandara
  3. Laksiri Gomes
  4. Tibutius Thanesh Pramanayagam Jayadas
  5. Achala Kamaladasa
  6. Dinuka Guruge
  7. Pradeep Darshana
  8. Thushali Ranasinghe
  9. Inoka Sepali Abyrathna
  10. Saubhagya Danasekara
  11. Buddini Gunathilaka
  12. Heshan Kuruppu
  13. Ananda Wijewickrama
  14. Ruwan Wijayamuni
  15. Lisa Schimanski
  16. T.K. Tan
  17. Graham S. Ogg
  18. Alain Townsend
  19. Gathsaurie Neelika Malavige
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Abstract

Background

While there have been many studies characterizing the IgG and IgA responses to different SARS-CoV-2 proteins in individuals with natural infection, the induction of IgG and IgA to different viral proteins in vaccinees have not been extensively studied. Therefore, we sought to investigate the antibody responses to SARS-CoV-2 following natural infection and following a single dose of AZD2221, in Sri Lankan individuals.

Methods

Using Luminex assays, we characterized the IgG and IgA responses in patients with varying severity of illness and following a single dose of the vaccine at 4 weeks and 12 weeks since onset of illness or following vaccination. Haemagglutination test (HAT) was used to assess the antibodies to the receptor binding domain of SARS-CoV-2 wild type (WT), B.1.1.7, B.1.351 and B.1.617.2 (VOCs) and surrogate neutralizing test to measure ACE2 receptor blocking antibodies.

Results

Those with mild illness and in vaccinees, the IgG responses to S1, S2, RBD and N protein increased from 4 weeks to 12 weeks, while it remained unchanged in those with moderate/severe illness. Those who had a febrile illness in 2017 and 2018 (controls) also gave IgG and IgA high responses to the S2 subunit. In the vaccinees, the most significant rise was seen for the IgG antibodies to the S2 subunit (p<0.0001). Vaccinees had several fold lower IgA antibodies to all the SARS-CoV-2 proteins tested than those with mild and moderate/severe illness at 4 weeks and 12 weeks. At 12 weeks the HAT titres were significantly lower to the B.1.1.7 in vaccinees and significantly lower in those with mild illness, and in vaccinees to B.1.351 and for B.1.617.2. No such difference was seen in those with moderate/severe illness.

Conclusions

Vaccinees had significantly less IgA to SARS-CoV-2, but comparable IgG responses to those with natural infection. However, following a single dose, vaccinees had reduced antibody levels to the variants of concern (VOC), which further declined with time, compared to natural infection.

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