Pathogens that infect over 600 million people! You may only know about one of them!

There has been a lot of popular science about "scarlet fever" recently, so I'd like to talk about the progress in the research and development of group A Streptococcus (GAS)-related diseases and vaccines.

1. Group A Streptococcus not only causes scarlet fever

Group A Streptococcus is also called "Streptococcus pyogenes". It is somewhat similar to Streptococcus pneumoniae, which can now be prevented by vaccines (PPSV23 and PCV13 have been approved in my country). After infection, both can be divided into "non-invasive infection" and "invasive infection" (see the figure below for details).

Among them, the non-invasive infections that people are more familiar with are "pharyngitis" and "scarlet fever". The former has typical symptoms of upper respiratory tract discomfort, and the most typical symptom of the latter is "strawberry tongue" (see the picture below).

Due to lack of knowledge, people may mistakenly believe that group A streptococcal infection is rare. However, according to the World Health Organization, "more than 100 million children" suffer from impetigo related to non-invasive group A streptococcal infection, and "more than 600 million people" suffer from pharyngitis due to group A streptococcal infection.

Invasive infections are more serious and include bacteremia, cellulitis, toxic shock syndrome, etc., which require prompt treatment.

In terms of complications, group A streptococcus causes 470,000 new cases of acute rheumatic fever and 288,000 new cases of rheumatic heart disease each year.

2. Research progress of streptococcal vaccines

Although after the invention of antibiotics, even group A streptococcus can infect people multiple times in their lifetime, as long as timely treatment is given, it generally does not cause serious consequences (the main risk is in low-income countries and regions). Therefore, compared with many serious diseases, research on group A streptococcal vaccines is not as urgent.

Judging from the public information of several well-known listed companies in the world, only "two" of the more mainstream companies are researching group A streptococcal vaccines (one in China and one in the United States), and both are in the preclinical stage.

Unlike group A Streptococcus, some companies are researching group B Streptococcus (GBS) vaccines. Compared with group A Streptococcus, group B Streptococcus is almost impossible to prevent and poses a great threat to newborns, pregnant women and people with weakened immune systems (see figure below).

Currently, two overseas companies' group B streptococci have entered Phase 2 clinical trials, and there is also a listed company in China that is also in the preclinical stage.

Interestingly, the American company's group A streptococcal vaccine is prepared using three antigens: "Streptococcus pyogenes adhesion and division protein" (SpyAD), "streptolysin O" and "C5a peptidase" (ScpA) (see figure below). In animal experiments, it was also found that this vaccine produced cross-protection against group B streptococci, but it is still a long way from being approved for marketing.

willing

=Pill=

Disclaimer: This article was created out of personal interest, only to help more ordinary people have a clearer understanding of vaccines. The content and views do not represent any organization, unit, or institution, and it has not accepted any form of sponsorship. All pictures are from public online platforms. If the content is incorrect, please do more self-criticism (not).