Immunogenicity of COVID-19 Vaccines in Tuberculosis Patients

In late 2020, COVID-19 pandemic was occurred globally. Like Tuberculosis (TB), severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is primarily affected in respiratory tract with increased risk of severe clinical complications especially in particular risk population like diabetic patients and old ages. Like other viral infections, there is evidence that both acquired humoral and cellular immunological responses against the SARS-CoV-2 infection are key in providing protective immunity. Although the magnitude and durability of both binding and neutralizing antibodies after seroconversion of COVID-19 patients are highly variable at the individual patient level, higher level of neutralizing antibodies appears to be correlated with protection against reinfection.

As natural immunity alone after COVID-19 infection appears to be insufficient for protection against COVID-19, since the beginning of COVID-19 pandemic, several COVID-19 vaccines developed based on different technical platforms have been introduced globally. Up to August 2021, twenty COVID-19 vaccines has been included in WHO's Emergency Use Listing (EUL).

As protection against COVID-19 infection among TB patients is critical to prevent severe clinical outcomes, COVID-19 immunization program is carrying out among TB patients in the SMRU TB centers with supply of COVID-19 vaccines from Ministry of public health, Thailand. In Thailand, Pfizer-BioNTech COVID-19 vaccine, AstraZeneca vaccine and Janssen Ad26.COV2.S COVID-19 vaccine are widely available in COVID-19 vaccination campaigns.

Pfizer-BioNTech COVID-19 vaccine is an mRNA vaccine and its two-dose regimen with inter-dose interval of 21 days apart can provide effective protection against SARS-CoV-2- infection. Mild local and systemic reactions can occur after vaccination but serious adverse effects can be complicated rarely. It can also be provided for children over 6 months of age and reactogenicity is also less frequent.

AstraZeneca vaccine is a replication-deficient chimpanzee adenovirus-vectored vaccine expressing full-length SARS CoV-2 spike glycoprotein gene. Efficacy, immunogenicity and safety profiles of the vaccine are acceptable and reasonably well tolerated in healthy young and old adults, symptomatic COVID-19 patients and people with HIV infection.

Janssen Ad26.COV2.S COVID-19 vaccine is a recombinant, replication-incompetent adenovirus serotype 26 (Ad26) vector encoding a full-length and stabilized SARS-CoV-2 spike protein. The vaccine needs single dose of administration intramuscularly into the deltoid muscle. Multicenter, placebo-controlled, phase 1-2a trial has shown that single dose of the vaccine has an efficacy of 66.9% against symptomatic COVID-19 infection, 76.7% against severe COVID-19 disease after 14 days, and 85.4% after 28 days. The vaccine appears to be safe like other COVID-19 vaccines because no severe allergic or anaphylactic reaction has been recorded in clinical trials except from occurrence of a very rare syndrome of blood clotting combined with low platelet counts in some countries. However, there has been no sufficient data on pregnancy and people with co-morbidity especially HIV/TB patients.

As there is limited knowledge about immunogenicity of COVID-19 vaccines among TB patients, examination of immunological responses from the COVID-19 vaccines offering in community COVID-19 vaccination campaigns among TB patients as well as healthy population is warranted. Protectability and immune response to the COVID-19 vaccines in TB patients under treatment should be studied to get better understanding about immunological responses among population with co-morbidity. Along with antibodies response, reactogenicity, clinical and laboratory safety profiles of the COVID-19 vaccines in this specific group will also be assessed and compared with the healthy control.

This study is a non-randomized observational study aimed to compare humoral and cellular immunological responses of the COVID-19 vaccines between bacteriologically confirmed TB patients under treatment cohort (n=54) vs healthy individuals (n=54) after receiving a COVID-19 vaccine. Each participant will receive single or double doses of one of aforementioned COVID-19 vaccines in the deltoid muscle of the non-dominant arm.

Follow-up appointments will be scheduled on 2nd dose visit and 28 days after 2nd dose in double dose scheduled COVID-19 vaccines and 28 days and 56 days after vaccination in single dose scheduled COVID-19 vaccine. For assessment of reactogenicity, participants will be informed to attend follow-up appointments every day for 7 days following each dose of vaccination.

Frequency, incidence and nature of solicited local and systemic adverse events (AEs) and unsolicited AEs will be recorded at their follow up visits. For immunological responses, humoral and cellular antibody level to SARS-CoV-2 virus will be assessed over time (before 1st dose, before 2nd dose , 28 days after 2nd dose in double dose scheduled COVID-19 vaccine or before single dose vaccination, 28 days and 56 days after vaccination in single dose scheduled COVID-19 vaccine) and compared between TB patients and healthy individuals. Baseline laboratory investigations such as liver function tests, renal function tests, serum electrolytes, iron, complete blood count and C reactive protein will be tested on Day 0 and rechecked on the same days as immunological tests to review changes after vaccination.

Infection serological tests such as Human immunodeficiency virus (HIV), Hepatitis B surface antigen (HBsAg), and Hepatitis C antibody (HCV Ab) tests will be performed at screening visit with consent of potential participants. Moreover, nasopharyngeal swab for COVID-19 PCR test will be tested before being enrolled. These tests can be repeated if there are symptoms suggestive of these infections.