Table 1.

Comparison of key issues for development of vaccines for SARS-CoV-2 and Mycobacterium tuberculosis infection.

	SARS-CoV-2	Tuberculosis	Notes
Key protective antigen	Spike protein	Number of key specific and cross-reactive antigens identified	M. tuberculosis genome encodes ∼4000 genes
Antigenic variation	Mutations common	Antigenic variation limited	Both SARS-CoV-2 and M. tuberculosis show strain variation in transmissibility
Immune correlates of protection	Neutralising antibodies considered key although T cells likely to play a role	Cell-mediated immunity critical although precise definition unclear. Role of humoral immunity also unclear.	Was not needed for the development of effective SARS-CoV-2 vaccines but would be game-changing in the development of a new TB vaccine
Categories of infection	Subclinical, clinical	Latent (incipient/subclinical) and clinical	In both infections, transmission may occur from subclinical infection
Time to develop disease	1-2 weeks	Can be years/decades/lifespan
Identification of pathogen	2019 with resulting pandemic	1882	WHO declared TB a global health emergency in 1994
Licensed vaccines by January 2022	4 (UK)	1 (BCG)	BCG first used in 1921
Vaccine candidates in Preclinical and clinical development	195 pre-clinical 146 clinical	Unknown but <50 14 clinical	SARS-CoV-2: WHO as at 02/2022; TB: TBVI as at 11/2021.