War in Tigray erased measles surveillance and left young children unvaccinated

The 2020–2022 war in Tigray did not just interrupt measles vaccination in the Ethiopian region — it made the resulting damage invisible, according to an analysis of national surveillance data [s1]. During the fighting, the number of measles cases reported from Tigray fell to 0·01% of Ethiopia's national total, a drop the authors read as near-total collapse of surveillance rather than an absence of disease [s1].

What that collapse concealed surfaced once reporting resumed. In the recovery period, the median age of a reported measles case in Tigray fell to five years, and confirmed cases were far more likely to be in children who had never received a measles vaccine [s1]. Both are the fingerprints of a cohort of susceptible young children that had been building unseen.

What the study did

Researchers conducted a retrospective longitudinal analysis of Ethiopia's national case-based measles surveillance data from 2018 to 2024, covering 69,866 records [s1]. They split the period into three phases — pre-conflict (2018–2019), the conflict peak (2020–2022) and post-conflict recovery (2023–2024) — and compared surveillance reporting, the age distribution of cases and vaccination status across them, using the pre-conflict years as the reference [s1].

The findings

The first result is the near-disappearance of Tigray from the national numbers: during the conflict peak, cases reported from the region amounted to 0·01% of the national total, consistent with a surveillance system that had stopped functioning rather than a population that had stopped getting measles [s1]. The system's degradation showed in its record-keeping too — during the conflict peak, 50% of confirmed cases in Tigray were missing sex-disaggregated data [s1].

The second result is the paediatric shift. After hostilities ended, the median age of infection in Tigray fell from 24·0 years during the conflict to 5·0 years in the post-conflict period (p < 0·0001) — a change not seen in other regions of Ethiopia [s1]. Measles concentrating in young children is what happens when routine immunisation lapses and susceptibility accumulates in a birth cohort that missed its shots.

The third result quantifies that immunity gap directly. Compared with the pre-conflict baseline, the adjusted odds that a confirmed measles case was zero-dose — in a child who had received no measles vaccine at all — were 71·43 times higher during the conflict peak (95% CI 14·1–1000·0), and remained 2·49 times higher during the recovery period (1·17–5·52) [s1]. The enormous confidence interval on the wartime figure reflects how few usable records the collapsed system produced; the post-conflict estimate is far more precise, and it shows the elevation persisting after the war formally ended.

The wider toll on mothers and infants

Measles surveillance is one thread of a broader unravelling. A separate retrospective cohort of 1,763 mothers at two hospitals in Mekelle found that the incidence of low birth weight nearly doubled over the same window, from 8·6% before the war to 17·2% during it (p < 0·001), with mothers who delivered during the war more than twice as likely to have a low-birth-weight infant (adjusted odds ratio 2·22, 95% CI 1·64–3·00) [s2]. The two datasets describe the same health system failing along different axes — antenatal care and routine immunisation alike.

Why it matters beyond Tigray

The practical warning is about timing. A susceptible cohort that builds during a conflict does not announce itself while surveillance is down; it becomes visible only afterward, as outbreaks in young children — by which point the window for quiet catch-up vaccination has narrowed. The authors' conclusion is that post-conflict recovery needs both resilient surveillance systems and targeted catch-up vaccination, precisely because the damage is largest at the moment it is hardest to see [s1].

The measured elevation in zero-dose odds through the recovery period [s1] is the concrete form of that risk: the children who missed measles vaccine during the war were, on this evidence, still under-immunised after it. That is a solvable problem, but only if the surveillance that would flag it is rebuilt first.

This article is informational and is not medical advice.

Sources

• [s1] "Effect of armed conflict on measles surveillance and zero-dose vaccination status in Tigray, Ethiopia, 2018–2024," Conflict and Health, 3 August 2026. https://doi.org/10.1186/s13031-026-00827-9
• [s2] "The impact of the Tigray War on the incidence of low birth weight in Tigray, Ethiopia: A retrospective cohort study," PLOS Global Public Health, 10 August 2026. https://doi.org/10.1371/journal.pgph.0006298