29 June = 2005

29=20 June 2005

Public Use=20 of Masks in Hong Kong during SARS 2003

Use=20 of masks by the public in Hong Kong, and not in Toronto, during the SARS = epidemic of 2003 is understandable and rational given the different = contexts in=20 which SARS occurred in these two locations. Criticism of the use of = masks by the=20 Hong Kong public as a =91fashion statement=92 or =91window dressing=92, = is unfounded and=20 counterproductive. Such criticism demonstrates a lack of understanding = regarding=20 the context of the initial SARS outbreak in Hong Kong ,and the fact that = a=20 similar disease in the USA, such as SARS, pandemic influenza, or plague=20 pneumonia could elicit the same mask-wearing response by the American = public in=20 affected cities.

According=20 to the World Health Organization (WHO), a total of 251 =93probable SARS = cases=94=20 were reported from Canada, and 1,755 probable SARS cases were reported = form Hong=20 Kong. In Canada the vast majority of patients were from the Greater = Toronto=20 Area, and nearly all were related to hospital exposure to the SARS = coronavirus.=20 The one major exception was a community outbreak involving a funeral and = a group=20 of 31 persons belonging to the same religious group who became infected = with the=20 SARS virus. Thus, it is understandable and rational that the general = public in=20 Toronto did not perceive a significant risk of becoming infected with = the SARS=20 virus and did not wear masks in public. =20 As a visiting physician who worked in a Toronto SARS-designated = hospital=20 (Scarborough General) in late June and early July 2003, and lived in a = downtown=20 hotel, it was obvious that there was no widespread sense of fear that=20 transmission of SARS was occurring outside of the health-care=20 facilities.

In=20 contrast, the SARS outbreak in Hong Kong began from room 911 of a large, = well-known hotel (=93M=94), where a physician visiting Hong Kong from = Guangdong=20 province, China, stayed for one night on February 21, 2003. Persons infected at this Hong = Kong=20 hotel, and their secondary contacts, soon were admitted to hospitals in = Hong=20 Kong and other places abroad. In Hong Kong, however, unlike Toronto, = SARS was=20 transmitted to a relatively large number of persons in community = settings early=20 during the outbreak (March 2003) before the name =93SARS=94 had even = been adopted=20 and when this new disease was still =20 referred to as an =93atypical pneumonia=94.

An=20 informative description of the epidemiology of all 1,755 SARS patients = in Hong Kong was published in = November 2004=20 by Gabriel Leung and colleagues from Hong Kong (Annals Internal Medicine = 2004;141:662-673). Notably, only half (49.3%) of SARS patients in Hong = Kong were=20 infected in hospitals, clinics, or elderly or nursing homes. Of note, an additional ~ 26.1% = of SARS=20 patients (totaling 458 persons) were infected in large residential = buildings in=20 Hong Kong, mstly in Block E of the Amoy Gardens apartment complex (330 = person or=20 ~18.8% of the 1,755 = total) and=20 =93nearby Amoy Gardens=94 residential buildings where relatives, friends = and other=20 contacts lived (128 person or ~7.3%). Another 47 persons (2.7%) were = infected in=20 residential buildings other than those near Amoy Gardens. =

Notably,=20 a further 152 persons (8.7% of the 1,755 total) also had = community-acquired SARS=20 infection. =93Of this = community=20 transmission, 64% (97 of = 152 cases)=20 could be attributed to intrafamilial or within-house-hold spread, = defined as=20 transmission from 1 household or family member to another with no known = sources=20 of infectious contact=94 (page 665). Thus, at least 657 persons = (330+128+47+152)=20 had community-acquired SARS virus infection in Hong Kong, most during March 2003 when this = novel=20 respiratory disease was still being defined and named, and public=20 health-infection control countermeasures were still being developed in = health=20 care facilities, such as the use of surgical mask and N-95 respirators.=20

A=20 2^nd highly informative publication from Hong Kong presents = data from=20 ten (10) telephone surveys performed between 21 March 2003 and 12 May = 2003=20 involving 1,397 Hong Kong residents that =20 documents the perceptions, concerns, and behaviours of the = general public=20 regarding the unfolding SARS outbreak (Lau JTF and colleagues. J = Epidemiology=20 and Community Health 2003;57:864-870). =20 In these surveys, the perceived efficacy of wearing a mask to = prevent=20 SARS infection increased from only 11.5% on March 21^st to a = striking=20 84.3% on April 1^st. = What=20 changed?

This=20 behavior is understandable and rational when examined in the context of = the=20 timeline of the SARS outbreak in Hong Kong. On or about March 26 the large (e.g., more than the = total number=20 of probable SARS cases in all of Canada) SARS outbreak involving the = Amoy=20 Gardens residential building area, and especially the Block E section, = became=20 widely known. On March 29 =93all classes in all schools in Hong Kong = were=20 suspended. On March 31, all block E residents of the Amoy Gardens estate = were=20 quarantined at home and all close contacts of SARS patients were = required to be=20 examined in designated clinics. On April 1, all block E Amoy Gardens = estate=20 residents were further moved to two quarantine camps=94 (page 864). From these facts, as well as = from=20 visiting Hong Kong in May 2003, I conclude that use of masks by a large part of the public in Hong Kong during the = SARS=20 outbreak was as understandable and rational as was not wearing masks in = Toronto,=20 given the respective contexts of SARS-transmission in these two=20 places.

Daniel=20 R.Lucey, MD, MPH

Adjunct=20 Professor of Microbiology and Immunology

Georgetown=20 University School of Medicine

Director,=20 Center for Biologic Counterterrorism and Emerging = Diseases

Department=20 of Emergency Medicine

Washington=20 Hospital Center

Washington,=20 DC

e-mail:=20 Daniel.R.Lucey@Medstar.net