, nine staff and 34 of its 37 residents were infected, four of whom died. The improvements in and implementations of infection control measures in LTCFs in Hong Kong were built on lessons learned from severe acute respiratory syndrome (SARS) epidemics in 2003, which affected 6.72% (51/759) of the LTCFs and 0.13% (72/54,754) of the LTCF residents, with a mortality rate of 78.1%. 2-4 Collaboration among medical, social welfare, and private sectors is the key to the early detection of cases and the prevention of spread during infectious outbreaks in LTCFs. Effective measures include training on proper infection control practices, the correct use of personal protective equipment, cohort formation and surveillance of LTCF residents recently discharged from hospitals during the epidemics, and hospitalbased community geriatric teams led by geriatric specialist to render support to LTCFs. The last is particularly important to reduce avoidable hospitalization by attending to the medical needs of frail older people. 4 The outreach role of geriatricians was found to be especially important during the 2003 SARS epidemic when scrutiny of cases among LTCF residents revealed that 81% had been hospital acquired and only 14% were acquired in LTCFs. 4 Among the reasons why LTCFs are so vulnerable to COVID-19, Lau-Ng et al 1 listed asymptomatic transmission as the "Achilles heel." 1 To this, I would add the longer incubation period of COVD-19 in older adults, 5 which predisposes to presymptomatic transmission. Transmission toward the end of the incubation period and before the onset of symptoms is more likely to occur during a long incubation period. 6 Arons et al 7 reported presymptomatic SARS coronavirus 2 (SARS-CoV-2) infections in half (24/48) of the residents tested positive for COVID-19 during an LTCF outbreak. Symptoms developed subsequently within a median of 4 days, and viable virus isolated up to 6 days before symptom onset. 7 A longer incubation period in older adults was suspected clinically during the 2003 SARS epidemic 2-4 and has been documented recently for SARS-CoV-2 during COVID-19 pandemic. 5 Knowledge of a longer COVID-19 incubation period (median = 11.2 days; 90th percentile = 17 days) in older adults 5 supports extending the duration of transmission-based precautions, isolation, and observation strategies for LTCF residents to minimize spread. [Correction added on October 14, 2020 after first online publication: In the preceding sentence, the reference citation was