Covid-19: Where are we on immunity and vaccines?BMJ 2020; 370 doi: https://doi.org/10.1136/bmj.m3096 (Published 05 August 2020) Cite this as: BMJ 2020;370:m3096
All rapid responses
We read with great interest the recent article by Elisabeth Mahase, titled: ‘Covid-19: Where are we on immunity and vaccines?’(1) - especially as evidence on the importance of SARS-CoV-2 T cells is emerging fast.
The piece mentions a comment by Professor Maini suggesting that current commercially available interferon gamma release assay (IGRAs) that are used to assess TB infection status may be adapted to assess T-cell response to SARS-CoV-2 infection. However, Prof. Maini also stated that the use of T-cells as an additional marker for prior infection is a long way from reality. However, Oxford Immunotec Ltd have already developed a commercially available, research use only, kit, T-SPOT® Discovery™ SARS-CoV-2, to measure T cell responses in subjects previously infected with SARS-CoV-2 virus.
This kit is based on the same technological ELISPOT platform as our T-SPOT.TB test that has been approved for clinical use to detect tuberculosis infection in over 50 countries including the US, Europe, China, and Japan and of which over 20 million tests have been used in healthcare.
This test was used in a recent, as yet unpublished, cross sectional study of 2,500 frontline workers, conducted to examine the SARS-CoV-2 antibody and T cell response in those reporting previous illness compatible with the COVID-19 clinical condition (some confirmed by polymerase chain reaction and others with only the clinical syndrome) and in those with no such history of infection. Initial study results suggest that the T-SPOT® Discovery™ SARS-CoV-2 Research Use Only (RUO) kit is able to identify T cell responses in the vast majority of infected patients. Moreover, some patients who were infected, but antibody negative demonstrated robust T-cell responses as identified by the T-SPOT® Discovery™ SARS-CoV-2 Kit.
Potential Use of the T-SPOT Discovery kit:
As has been shown, antibody titres to SARS-CoV-2 may decay over time leading to a potential inability of tests to identify those previously infected (2,3). This may be important in the future with the possibility of the much vaunted ‘immune passport’. The T-cell assay may also be of benefit in identifying an appropriate humoral immune response to a vaccine candidate during at the development stage. However, perhaps a less obvious use would be to help confirm the ‘previously uninfected’ status of vaccine trial participants thus not enrolling potentially immune subjects into the placebo arm of a trial thus eliminating a potential source of selection bias.
The current commercial availability of a ‘research use only’ SARS-CoV-2 T-cell test should allow a more widespread assessment of the humoral response to this virus, especially in the situation where the antibody response may be more transient.
1. Mahase E. Covid-19: Where are we on immunity and vaccines? BMJ [Internet]. 2020 Aug 5 [cited 2020 Aug 17];370. Available from: https://www.bmj.com/content/370/bmj.m3096
2. Altmann DM, Boyton RJ. SARS-CoV-2 T cell immunity: Specificity, function, durability, and role in protection. Sci Immunol. 2020 Jul 17;5(49):eabd6160.
3. Ibarrondo FJ, Fulcher JA, Goodman-Meza D, Elliott J, Hofmann C, Hausner MA, et al. Rapid Decay of Anti–SARS-CoV-2 Antibodies in Persons with Mild Covid-19. N Engl J Med. 2020 Jul 21;0(0):null.
Competing interests: No competing interests
There seems to be a great rush for bringing SARS-CoV-2 Vaccines in market. People are also eager for the Vaccine. In ordinary course a drug takes about 10 years from concept to market. If a drug is fast-tracked, it still rakes about 3 years to be approved for use.
One has to be wary of haste in marketing Vaccines. Following points must be kept in mind:
1) How long the Immunity conferred by the Vaccine will last?
2) If the virus mutates, will the Vaccine protect against the new mutant?
3) Will the vaccine protect people of all the geographic and ethnic origins equally well?
4) Will the vaccine be suitable for people of all ages?
5) Will there be very late onset adverse effects of the vaccine?
Very late onset adverse effects such as Subacute Sclerosing Pan Encephalitis (SSPE), cannot be ruled out with short duration trials.
Adverse effects like Subacute Sclerosing Pan Encephalitis, Ascending Polyneuritis, Myopathies, Autoimmune Diseases,and rarer chance of triggering development of malignancies are most dreaded possibilities.
Also worrisome prospects are that should any of these adverse effects develop, people will lose faith in vaccination and anti-vaccine campaigns will get a stick to beat with.
The rush for the vaccines should not lead to a disaster.
Arvind Joshi; MBBS, MD, FCGP, FAMS, FICP;
Convener- Our Own Discussion Group;
602-C, Megh Apartments;
Ganesh Peth Lane, Dadar West, Mumbai;
Maharashtra State, INDIA; PIN 400028.
Competing interests: No competing interests