inclusion criteria: * inclusion criteria for ltchs: 1. ltch in ontario with \>80% of residents being adults ≥65 years of age. 2. residents are or can be routinely assessed at least daily by staff. 3. ltch has not previously had a unit enrolled in this study. 4. outbreak of covid-19 declared on at least one nursing unit, requiring all of the following: 1. ≥2 to ≤4 residents who develop pcr-confirmed symptomatic covid-19 infection on the same unit within ≤ 7 days at the time when the outbreak is identified as eligible. 2. ≤21 days from symptom onset in the index case at the time when the outbreak is identified as eligible. 3. cumulative attack rate in residents on the affected unit since the beginning of the pandemic ≤25% at the time when the outbreak is identified as eligible. 4. ≤20% of residents with microbiologically confirmed covid-19 or line-listed as a presumptive case in a covid-19 outbreak and not tested for covid-19 in prior outbreaks within the last six months. 5. nursing unit with ≥16 and ≤32 residents. 6. nursing home agrees to work with study coordination to minimize the number of persons who provide care on the unit. 5. mechanism exists for delivery of medication and recording of administered medication for all residents. 6. ≥80% of residents on outbreak unit are eligible and they or their substitute decision makers consent to participate in the study. 7. written informed consent of medical director, administrator and a delegate of the residents' council of the ltch for ltch to be included in the cluster trial. * inclusion criteria for ltch residents: 1. informed consent from resident or substitute decision maker (sdm) * inclusion criteria for ltch staff: 1. expected to work at least two 8-hour shifts, or the equivalent time (16 hours on the unit) during the outbreak period. 2. informed consent.

inclusion criteria: * inclusion criteria for ltchs: 1. ltch in ontario with \>80% of residents being adults ≥65 years of age. 2. residents are or can be routinely assessed at least daily by staff. 3. ltch has not previously had a unit enrolled in this study. 4. outbreak of covid-19 declared on at least one nursing unit, requiring all of the following: 1. ≥2 to ≤4 residents who develop pcr-confirmed symptomatic covid-19 infection on the same unit within ≤ 7 days at the time when the outbreak is identified as eligible. 2. ≤21 days from symptom onset in the index case at the time when the outbreak is identified as eligible. 3. cumulative attack rate in residents on the affected unit since the beginning of the pandemic ≤25% at the time when the outbreak is identified as eligible. 4. ≤20% of residents with microbiologically confirmed covid-19 or line-listed as a presumptive case in a covid-19 outbreak and not tested for covid-19 in prior outbreaks within the last six months. 5. nursing unit with ≥16 and ≤32 residents. 6. nursing home agrees to work with study coordination to minimize the number of persons who provide care on the unit. 5. mechanism exists for delivery of medication and recording of administered medication for all residents. 6. ≥80% of residents on outbreak unit are eligible and they or their substitute decision makers consent to participate in the study. 7. written informed consent of medical director, administrator and a delegate of the residents' council of the ltch for ltch to be included in the cluster trial. * inclusion criteria for ltch residents: 1. informed consent from resident or substitute decision maker (sdm) * inclusion criteria for ltch staff: 1. expected to work at least two 8-hour shifts, or the equivalent time (16 hours on the unit) during the outbreak period. 2. informed consent.

inclusion criteria: inclusion criteria for ltchs: ltch in ontario with >80% of residents being adults ≥65 years of age. residents are or can be routinely assessed at least daily by staff. ltch has not previously had a unit enrolled in this study. outbreak of covid-19 declared on at least one nursing unit, requiring all of the following: ≥2 to ≤4 residents who develop pcr-confirmed symptomatic covid-19 infection on the same unit within ≤ 7 days at the time when the outbreak is identified as eligible. ≤21 days from symptom onset in the index case at the time when the outbreak is identified as eligible. cumulative attack rate in residents on the affected unit since the beginning of the pandemic ≤25% at the time when the outbreak is identified as eligible. ≤20% of residents with microbiologically confirmed covid-19 or line-listed as a presumptive case in a covid-19 outbreak and not tested for covid-19 in prior outbreaks within the last six months. nursing unit with ≥16 and ≤32 residents. nursing home agrees to work with study coordination to minimize the number of persons who provide care on the unit. mechanism exists for delivery of medication and recording of administered medication for all residents. ≥80% of residents on outbreak unit are eligible and they or their substitute decision makers consent to participate in the study. written informed consent of medical director, administrator and a delegate of the residents' council of the ltch for ltch to be included in the cluster trial. inclusion criteria for ltch residents: 1. informed consent from resident or substitute decision maker (sdm) inclusion criteria for ltch staff: expected to work at least two 8-hour shifts, or the equivalent time (16 hours on the unit) during the outbreak period. informed consent.

inclusion criteria: inclusion criteria for ltchs: ltch in ontario with >80% of residents being adults ≥65 years of age. residents are or can be routinely assessed at least daily by staff. ltch has not previously had a unit enrolled in this study. outbreak of covid-19 declared on at least one nursing unit, requiring all of the following: ≥2 to ≤4 residents who develop pcr-confirmed symptomatic covid-19 infection on the same unit within ≤ 7 days at the time when the outbreak is identified as eligible. ≤21 days from symptom onset in the index case at the time when the outbreak is identified as eligible. cumulative attack rate in residents on the affected unit since the beginning of the pandemic ≤25% at the time when the outbreak is identified as eligible. ≤20% of residents with microbiologically confirmed covid-19 or line-listed as a presumptive case in a covid-19 outbreak and not tested for covid-19 in prior outbreaks within the last six months. nursing unit with ≥16 and ≤32 residents. nursing home agrees to work with study coordination to minimize the number of persons who provide care on the unit. mechanism exists for delivery of medication and recording of administered medication for all residents. ≥80% of residents on outbreak unit are eligible and they or their substitute decision makers consent to participate in the study. written informed consent of medical director, administrator and a delegate of the residents' council of the ltch for ltch to be included in the cluster trial. inclusion criteria for ltch residents: 1. informed consent from resident or substitute decision maker (sdm) inclusion criteria for ltch staff: expected to work at least two 8-hour shifts, or the equivalent time (16 hours on the unit) during the outbreak period. informed consent.

inclusion criteria: - inclusion criteria for ltchs: 1. ltch in ontario with >80% of residents being adults ≥65 years of age. 2. residents are or can be routinely assessed at least daily by staff. 3. ltch has not previously had a unit enrolled in this study. 4. outbreak of covid-19 declared on at least one nursing unit, requiring all of the following: 1. ≥2 to ≤4 residents who develop pcr-confirmed symptomatic covid-19 infection on the same unit within ≤ 7 days at the time when the outbreak is identified as eligible. 2. ≤21 days from symptom onset in the index case at the time when the outbreak is identified as eligible. 3. cumulative attack rate in residents on the affected unit since the beginning of the pandemic ≤25% at the time when the outbreak is identified as eligible. 4. ≤20% of residents with microbiologically confirmed covid-19 or line-listed as a presumptive case in a covid-19 outbreak and not tested for covid-19 in prior outbreaks within the last six months. 5. nursing unit with ≥16 and ≤32 residents. 6. nursing home agrees to work with study coordination to minimize the number of persons who provide care on the unit. 5. mechanism exists for delivery of medication and recording of administered medication for all residents. 6. ≥80% of residents on outbreak unit are eligible and they or their substitute decision makers consent to participate in the study. 7. written informed consent of medical director, administrator and a delegate of the residents' council of the ltch for ltch to be included in the cluster trial. - inclusion criteria for ltch residents: 1. informed consent from resident or substitute decision maker (sdm) - inclusion criteria for ltch staff: 1. expected to work at least two 8-hour shifts, or the equivalent time (16 hours on the unit) during the outbreak period. 2. informed consent.

inclusion criteria: - inclusion criteria for ltchs: 1. ltch in ontario with >80% of residents being adults ≥65 years of age. 2. residents are or can be routinely assessed at least daily by staff. 3. ltch has not previously had a unit enrolled in this study. 4. outbreak of covid-19 declared on at least one nursing unit, requiring all of the following: 1. ≥2 to ≤4 residents who develop pcr-confirmed symptomatic covid-19 infection on the same unit within ≤ 7 days at the time when the outbreak is identified as eligible. 2. ≤21 days from symptom onset in the index case at the time when the outbreak is identified as eligible. 3. cumulative attack rate in residents on the affected unit since the beginning of the pandemic ≤25% at the time when the outbreak is identified as eligible. 4. ≤20% of residents with microbiologically confirmed covid-19 or line-listed as a presumptive case in a covid-19 outbreak and not tested for covid-19 in prior outbreaks within the last six months. 5. nursing unit with ≥16 and ≤32 residents. 6. nursing home agrees to work with study coordination to minimize the number of persons who provide care on the unit. 5. mechanism exists for delivery of medication and recording of administered medication for all residents. 6. ≥80% of residents on outbreak unit are eligible and they or their substitute decision makers consent to participate in the study. 7. written informed consent of medical director, administrator and a delegate of the residents' council of the ltch for ltch to be included in the cluster trial. - inclusion criteria for ltch residents: 1. informed consent from resident or substitute decision maker (sdm) - inclusion criteria for ltch staff: 1. expected to work at least two 8-hour shifts, or the equivalent time (16 hours on the unit) during the outbreak period. 2. informed consent.