coefficientgiving.substack.com/p/announcing-the-strep-a-vaccine-fund

By the article’s publication date (May 26, 2026), there were already more than four Strep A vaccine candidates with human testing.

Examples documented in primary sources include:

1. 6-valent recombinant M-protein vaccine — a JAMA phase 1 trial in healthy adults reported that researchers "performed a phase 1 trial" of a vaccine containing fragments from 6 M types.
2. 26-valent GAS vaccine (StreptAvax) — published human studies reported adults receiving a 26-valent vaccine in phase I/II testing.
3. 30-valent StreptAnova — a published paper states: "We completed a Phase I trial" of the 30-valent M-protein vaccine.
4. MJ8VAX — a published randomized clinical trial says a Phase I clinical trial was conducted in healthy adults.
5. J8-K4S2 / p*17-K4S2 peptide candidates — ClinicalTrials.gov records a phase 1 trial randomizing volunteers to J8-K4S2 vaccine or p*17-K4S2 vaccine, meaning these candidates also entered human testing.
6. StreptInCor — ClinicalTrials.gov lists an active Phase I/IIa human trial.
7. GSK 4-component Strep A vaccine — ClinicalTrials.gov lists a Phase 1 first-in-human study with an actual start date of July 31, 2025, which is before this article was published.

So the statement "only four candidates have been tested in humans" is too low. Even using a conservative count, the primary literature and trial registries show at least five, and more likely six or seven, distinct Strep A vaccine candidates had already been tested in humans by late May 2026.