COVID-19 Outbreaks: Information and Protocols

COVID-19 Outbreaks: Information and Protocols

What constitutes an outbreak of COVID-19? 

While details may vary depending on the setting, an outbreak of COVID-19 is generally defined as 3 or more epidemiologically linked cases within a 14 day period.  A “major outbreak” is labeled by CalOSHA as 20 or more cases epidemiologically linked within 2 weeks; while CalOSHA technically only applies to employees/workplace exposure, similar criteria are often applied elsewhere. 

What is the public health protocol during a COVID-19 outbreak?

As always, once positive cases have been identified, the UHS COVID Response Team and/or Public Health employees interview cases to determine where/when they may have been infected and how long they are likely to be infectious, and who they may have already exposed (“contacts”); cases are also issued isolation orders and offered medical, mental health, and logistical support.  Contacts are then advised of their exposure and to follow the standard next steps, in accordance with local health orders, to mask and remain alert for symptoms for 14 days following contact, to test 3-5 days later, and - if unvaccinated only - to quarantine.

What differs in an outbreak depends, again, on the setting (health care facilities, for example, are held to a higher standard), and is determined in consultation with the local public health jurisdiction,  but standard protocol includes reviewing and improving infection control measures (e.g. masking, distancing, ventilation) and recommending weekly testing of all exposed -- particularly if unvaccinated.  If the outbreak is “major” the recommendation changes to twice-weekly testing, regardless of vaccination status.  This testing continues until there is no longer evidence of sustained increased transmission - practically, that means there are no more epidemiologically linked cases over a 14 day period.

Why/how do COVID-19 outbreaks [still] happen?

The delta variant of SARS-CoV-2 (the virus that causes COVID-19) is highly infectious, and while vaccination is highly protective against severe disease, it is less effective in preventing infection.  Similarly, while current evidence suggests that vaccinated infected individuals shed virus for fewer days than unvaccinated individuals, and thus overall they are likely to infect fewer people, they are still infectious, especially while symptomatic.  Thus: if infected individuals are in close contact with others - especially if indoors, unmasked - the virus will spread, and the more infectious people are in a space at the same time, the more likely that spread can turn into an outbreak.

How does campus work with Berkeley Public Health during outbreaks?

The UHS COVID Response Team has delegated authority by the City of Berkeley Public Health Department to perform COVID-19 case investigation and contact tracing on UCB students; UHS Occupational Health performs workplace investigations when employees test positive, in collaboration with EH&S and in accordance with CalOSHA regulations.  The COVID Response Team and campus health leadership have worked closely with the City of Berkeley public health officer throughout the pandemic (and before!), and in an outbreak situation, rely on their expertise and guidance.  On occasion, the California Dept of Public Health may in addition be consulted.

How is it determined when cases may be released from isolation?

In most cases,* people who test positive for COVID-19 are placed in isolation for 10 days, and released on day 11.  The start of this timeline is based on the case interview.  If people seek testing due to symptoms, the start date is generally the first day of symptoms; if people do not have symptoms, the clock starts from the date of the first positive test.  In an outbreak, the start date may be set as the test date in order to contain spread - this is because an outbreak by definition means spread is out of control and standard precautions and response have not worked.

*People who are immunocompromised may shed virus for longer periods thus are usually kept in isolation for 20 days or more.

How is it determined when cases may be released from quarantine?

In an outbreak situation, quarantine may be extended from the current 7 days (with negative testing day 5 or beyond) to 10 or even 14 days, subject to the judgment of the outbreak team.  Only unvaccinated* individuals are required to quarantine.

*Unvaccinated = not 2 weeks out from a completed primary COVID-19 vaccine (series); boosters not currently considered in this context.