Unvaccinated Texans were far more likely to catch Covid-19 or die from the disease than vaccinated residents during the coronavirus’ September spike, state health officials said Monday, as Texas grapples with a larger weekly Covid-19 death toll than any other state — and a lower-than-average vaccination rate.

From early September to October 1, vaccinated Texans were 13 times less likely to test positive for Covid-19 and 20 times less likely to die from the coronavirus than their unvaccinated peers, according to a Texas Department of State Health Services study.

Some 81.3% of the nearly 4,500 coronavirus deaths studied over that time period were among unvaccinated people, whereas 13.7% of deaths were tied to fully vaccinated Texans and 5% were among partially vaccinated patients, researchers said.

The gulf between vaccinated and unvaccinated Texans is somewhat larger if data from earlier in the year is included: From mid-January to early October, unvaccinated people made up 85.5% of the state’s total Covid-19 deaths and were 40 times more likely to die.

The study suggested “the proportion of cases and deaths among vaccinated people is expected to rise” as vaccination rates increase, and said effectiveness varies depending on patients’ immune systems or whether their immunity has worn off over time.

Similarly, a recent study from the Centers for Disease Control and Prevention found vaccinated Americans were 11.3 times less likely to die of Covid-19 than unvaccinated people from late June to mid-July, though the vaccines were slightly more effective at stopping infections, hospitalizations and deaths before the virus’ delta variant took root in June.