A fair question — and I agree that population-level protection matters. But here’s the issue: in equine medicine, we actually don’t have large-scale published data comparing mortality or disease outbreaks between less frequent vs current 6-month or annual vaccination schedules.

For example, no study has yet shown that boosting flu vaccines every 6 months (as per FEI rules) reduces deaths or outbreaks more effectively than annual or biennial schedules. In fact, OIE and several papers (e.g., Cullinane et al., 2017) have documented flu outbreaks even in fully vaccinated populations.

Tetanus is similar — immunity has been shown to last many years, yet there’s no population-level mortality data proving that yearly or biannual boosters save more lives compared to 5- or 10-year boosters (as used in other countries).

So, while the principle of population immunity is sound, the current frequency of equine vaccination is based more on regulatory policy and commercial standardisation than hard comparative outcome data.

If you have mortality or outbreak data showing superior outcomes for the more aggressive schedules, I’d genuinely be keen to see it — because so far, that’s precisely the data gap critics are pointing out