Table 3. Summary of studies of NPIs for COVID-19.
| NPI | Summary/results | Source/reference |
|---|---|---|
| Case detection |
(27%–37%) cases detected† |
Bhatia et al., unpub. data, https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Imperial-College-COVID19-international-surveillance-21-02-2020.pdf |
| Case detection |
38% (22%–64%) cases detected |
Niehus et al., unpub. data, https://www.medrxiv.org/content/10.1101/2020.02.13.20022707v2 |
| Case screening and detection |
(36%–65%) cases detected† |
Pinotti et al., unpub. data, https://www.medrxiv.org/content/10.1101/2020.02.24.20027326v1 |
| Case isolation and contact tracing |
Delay of symptom onset to isolation has a high impact on the results, affecting the controllability of the outbreak. Results vary by scenario. |
(51) |
| Travel screening |
34% (20%–50%) of travelers identified through both departure and arrival screening using symptoms or risk screening |
Gostic et al., unpub. data, https://www.medrxiv.org/content/10.1101/2020.01.28.20019224v2 |
| Travel screening |
46.5% (35.9%–57.7%) travelers not detected through thermal screening |
(52) |
| Travel screening |
Syndromic screening and traveler sensitization in combination could delay outbreaks in yet unaffected countries up to 83 d (75% 36 d, 97.5% 8 d). |
Clifford et al., unpub. data, https://cmmid.github.io/topics/covid19/screening-outbreak-delay.html |
| Travel reduction (transport suspension) |
Delay of 2.91 d (95% CI 2.54–3.29) for the arrival of the disease to other cities in China |
(53) |
| Travel reduction (travel quarantine) |
130 cities in China had >50% chance of having a COVID-19 case imported from Wuhan in the 3 weeks preceding the quarantine. |
(18) |
| Travel restrictions |
Travel restriction imposed on Wuhan delay the epidemic for 3 d. |
(15) |
| Travel reduction (airline suspensions) |
Travel restriction imposed on China will delay the disease in other countries, the biggest delay being in Africa (11 d) and South America (9 d). |
Adiga et al., unpub. data, https://www.medrxiv.org/content/10.1101/2020.02.20.20025882v2 |
| Travel reduction |
Travel restriction will delay the epidemic for 2 d. |
(54) |
| Cancellation of mass gathering |
37% fewer cases when the interventions started before the first case |
(53) |
| Combination of NPI |
66%, 86%, and 95% fewer cases depending on timing of the interventions |
Lai et al., upub. data, https://www.medrxiv.org/content/10.1101/2020.03.03.20029843v3.full.pdf |
| Combination of NPI |
50% fewer cases if transmissibility reduced by 25% in all cities in China; delay of epidemic peak for 1 month |
(11) |
| Combination of NPI |
Drastic control measures implemented in China have substantially mitigated spread of COVID-19. |
(36) |
| Combination of NPI |
Earlier intervention of social distancing could limit the epidemic in mainland China. Number of infections could be reduced up to 98.9%, and number of deaths could be reduced by up to 99.3% as of Feb 23, 2020. |
Zhang et al., unpub. data, https://www.medrxiv.org/content/10.1101/2020.03.04.20031187v1 |
| Community behavior modification | At least 42% of persons interviewed have modified daily behavior. | (55) |
*COVID-19, coronavirus disease; NPI, nonpharmaceutical interventions. †Point estimates