The Case for Eliminating COVID-19 Transmission
With the conversation about COVID-19 shifting to herd immunity and mass vaccination, it’s still helpful to reflect on how some countries handled the pandemic. COVID-19 spread globally by early 2020 and vaccines weren’t ready until spring 2021. Without them, herd immunity was surrounded by questions; how long would it take to make an effective vaccine? How many people need to be vaccinated in order to block COVID-19 transmission? Would the pandemic resolve on its own in 2021? Would the COVID-19 vaccine end up as regular as the flu vaccine? More importantly, and bearing in mind that most people in low salary countries will not be able to get a vaccine soon, what could be done to control and minimize COVID-19 while it is spreading without any vaccine?
Some countries became ‘COVID-free’ within months after their first outbreak while others have seen continuous ‘waves’ of cases in different hotspots over time. New Zealand, Taiwan, and Vietnam are among several countries that successfully minimized the impact of COVID-19 and may have set a new standard for handling pandemics with a new ‘elimination’ approach. In this article, elimination means eliminating the chains of transmission within a region until there are no new cases of COVID-19. Eradication means the disease is completely destroyed and reduced to zero on a global scale.
Photo: Shops closing temporary to limit COVID-19 transmission.
New Zealand is geographically isolated, which raised concerns that the pandemic would spread widely in February 2020: university students arrived from Europe and mainland China around tourist season. If the virus spread rapidly, it would not only strain the healthcare system but it would also place disparate burdens on the country’s native Maori and Pacific Islander populations. New Zealand first addressed the situation with a mitigation response strategy, using border-control policies and preparing hospitals for the rise in imported cases. Mitigation got the imported cases under control, but community transmission was still ongoing. Because laboratory testing capacities and contact tracing focused on imported cases, not enough resources were available for the growing number of cases within small communities.
While mitigation slowly progresses toward stricter response measures over time to ‘flatten the curve’, it became clear that NZ needed to switch gears. Response guidance moved away from national flu epidemic mitigation plans in mid-March. A four-tier response system began at Level 2 on March 21, 2020. Level 2 imposed severe travel restrictions, social distancing, and limitations for mass gatherings. This allowed for isolation and containment to trace suspected cases after blocking imported COVID-19. In light of active local transmission, escalation to Level 4 on March 25 was needed to shut down the sources causing chains of transmission within communities. All schools and non-essential services were shut down with a national emergency in effect to enforce stay-at-home orders.
By using strict measures early on, New Zealand eliminated its first outbreak in only 4 months. New Zealand fully de-escalated down to Level-1 restrictions and was declared ‘COVID-19 free’ on June 9 2020. Thanks to the elimination strategy, it had one of the lowest cumulative number of cases, incidence rates, and mortality rates among higher-income countries, including a lowered overall disease disparity for high-risk groups. Early risk-informed action allowed NZ to soon resume regular activity. As of this writing, New Zealand has only seen 26 deaths out of a cumulative 2,644 cases after a second wave thanks to these proactive measures.
COVID-19 isn’t the first coronavirus epidemic Taiwan has faced; in 2003 Asia dealt with outbreaks of a then-new coronavirus strain called Severe Acute Respiratory Syndrome (SARS-CoV). Home to nearly 24 million people with economic ties to mainland China, Taiwan was (and still is) at higher risk of imported cases. Guangdong and Hong Kong were epicenters linked to travel. In those five months, the uncertainty of SARS threatened Taiwan’s economy and healthcare system. The first SARS cases were reported on March 14 of 2003. That same day, Taiwan’s government formed a response system with the Department of Health to focus on surveillance. A Task Force Committee maintained a rapid-assessment quarantine system by assigning medical aid teams to review cases within three days of a report. By 28 March, Taiwan’s government established procedures for handling the spread: healthcare workers at SARS treatment hospitals were also guaranteed personal protective equipment (PPE) and N-95 masks.
As a further measure of surveillance, suspected SARS cases were reported to Taiwan’s Department of Health so public health workers could trace contacts and place them under home quarantine. Cases were assessed for a history of exposure to individuals with SARS or areas affected by it; symptoms and signs were also reviewed with WHO criteria for confirming SARS. Another important step Taiwan took was isolating both probable and suspected cases early on. Standard procedure was to prepare isolation rooms with HEPA air filters, negative pressure, and separate bathrooms so that SARS patients were kept away from the general hospital population. This was the main way of handling probable cases until the hospital system exceeded its capacity for negative pressure rooms between April 23 and May 8. Individuals identified for quarantine were split into two classes: Class A were healthcare workers exposed outside of isolation facilities, close contacts of confirmed patients, and those who boarded a flight within three rows of a SARS patient. People who weren’t exposed to a SARS patient or an infected healthcare worker had to home quarantine for the incubation period. Class B individuals were travelers from a SARS-affected area between April 28 to July 4. Quarantine for 10 days was required at home, an airport transit hotel, or an employer-assigned quarantine site. Government quarantine centers were also available.
On June 9, 2003 quarantine measures were eased so employees from China-based Taiwanese businesses could travel with masks. Quarantined individuals were required to self-monitor their body temperature and report by phone three times a day. Local public health nurses would deliver meals. Masks had to be worn at home if any area was shared with others in the household. If the person became sick while in quarantine, an ambulance would be arranged to transport them to the hospital. The driver would wear a Tyvek suit, gloves, and an N-95 mask. Taiwan’s CDC established 17 mobile containment teams early on, made up of frontline healthcare workers from Taiwan’s CDC and County Department of Health and United States CDC staff between March and May 2003. The teams had doctors and nurses assigned to evaluate hospital infection control practices. Checklists were used and isolation rooms were tested for sustained negative pressure. Standard equipment for evaluations included PPE and a specimen cooler to hold nasal swabs, culture media, and blood samples.
As the SARS epidemic petered out, Taiwanese officials found that early containment allowed for better outcomes without straining resources. However, improvements were still needed for infection control. In late April an outbreak of SARS occurred in Hospital ‘H’ that caused case clusters in eight other Taipei hospitals. A worker with a fever on April 12 interacted with staff, visitors, and patients in the emergency department. He was admitted on the 16th due to worsening symptoms but wasn’t suspected of SARS or moved to isolation until the 18th. Since the employee slept in the hospital’s basement quarters and socialized off-duty, it was estimated that up to 10,000 patients and visitors were potentially exposed in the six days he was symptomatic. Hospital H quarantined staff, patients, and visitors on April 24. One less center was available to prepare for the wave of new cases. As a result, the virus spread to other cities in Taiwan before exposed people tested positive. If future epidemics like SARS were to strike again, infection control practices needed improvement.
When COVID-19 emerged, Taiwan long had the infrastructure needed to withstand outbreaks of diseases like SARS. In 2004, Taiwan founded the National Health Command Center to work closely with the CDC and monitor emerging health threats. Surveillance systems again played a crucial role in guiding the pandemic response, coordinated by Taiwan’s CDC and the Central Epidemic Command Center. When a woman returning from Wuhan on January 21st 2020 was Taiwan’s first confirmed case of COVID-19, event-based surveillance systems led to screening airline passengers returning from Wuhan. All were placed under a 14-day mandatory quarantine. This first measure served Taiwan well in case control; between January and February, almost half of the 46 confirmed cases were imported from China. At first, Taiwan only considered travel to Wuhan and a fever/upper respiratory infection as COVID-19 criteria. When cases peaked in March 2020, COVID criteria expanded to include general travel and pneumonia with suspected symptoms. These changes coincided with border control escalations of travel alert levels (level 3 being a global travel alert).
As of this writing, Taiwan’s cumulative COVID cases are just over 1,100 with a mortality rate of only 1% (12 deaths). For comparison, 181 of the 668 SARS cases from 2003 were fatal (27%). The 2003 SARS epidemic allowed Taiwan to understand the nature of how coronaviruses can spread. Newer infrastructure was set up to support rapid assessment and isolation of new cases. Proximity in geography and economy to the Wuhan epicenter was also a factor for using surveillance, assessment, and restriction to contain transmission.
With a population of more than 96 million people, it may be surprising to discover that only 35 deaths occured from the 3,000 officially reported cases of COVID-19 as of this writing. After SARS, Vietnam took a proactive approach with how it would face similar situations. COVID-19 was not yet identified when it began to appear in China during December 2019, but its contagious nature as a respiratory illness put Vietnamese officials on alert. Travelers entering Vietnam from Wuhan were monitored out of precaution before the first case of COVID-19 was confirmed on January 23, 2020. Vietnam faced two distinct waves of COVID-19 and emerged from both with an astonishingly low mortality.
The first wave of COVID-19 proceeded in two distinct phases. Phase 1 began January 23 2020 with the first case, prompting the government to work with the Deputy Prime Minister and establish the National Steering Committee for COVID-19 Prevention and Control. Contact tracing was carried out for confirmed cases. The government also shut down schools, public transportation, cancelled public events, and restricted international travel. In response to concerns of mass panic-buying among Vietnamese citizens, the government made and distributed face masks while watching for spikes in market goods. The first phase focused on detection and treatment of 16 cases from 4 cities and provinces linked to Wuhan in China. All of which recovered and ended with the last patient’s discharge on February 25 2020. After Phase 1 was declared over by February 13, Vietnam was COVID-free for all but 20 days before a larger second wave of cases erupted.
Phase 2 began on March 6 with the detection of new cases ‘imported’ by Vietnamese travelers from Europe and the USA. Disease clusters appeared in areas of high population density with more asymptomatic people spreading the virus. The government prohibited international travel to Vietnam starting March 15 2020 and imposed mass quarantining on the 16th. Anyone who had direct contact with a confirmed case or entered Vietnam from COVID-infected countries were required to self-isolate. More drastic measures included quarantining entire buildings, streets, and communities on the block where a case was detected. Health professionals and those who worked for their community formed Rapid Action Teams to spread local awareness about COVID-19 and educate others about preventive health practices (i.e. handwashing and masks). Additionally, Vietnamese authorities enforced a national lockdown on April 1-15, 2020. Phase 2 lasted 76 days with an average of 4.1 new cases confirmed each day for a total of 308.
Reducing community transmission on multiple levels of action resulted in zero fatalities for the first wave of COVID. While cases were mainly treated at local facilities to reduce strain on specialist hospitals, this approach revealed how hospital practices can influence the outcome of an epidemic. National social distancing and travel restrictions were lifted in April, which allowed tourism and public entertainment to resume. Vietnam remained COVID-free until July 25, 2020 when a second outbreak occurred. The epicenter was a hospital in Da Nang, Vietnam’s largest tourist city. Between July 1 and July 27 2020, up to 2 million people left Da Nang and traveled to other Vietnamese provinces with 41,000 visiting Da Nang Hospital. Containment strategies depended on a province’s local testing capacity and contact tracing resources. To supplement quarantine orders and travel restrictions, some provinces mass-tested 100,000 people using the rapid antibody test. More people could be tested but rapid tests were more likely to give false negatives for asymptomatic and early-stage cases compared to RT-PCR tests. As a consequence, re-testing suspected cases and their contacts inevitably consumed more resources.
Each wave became less predictable and required complex problem-solving. While the second wave only had 35 deaths out of 1,049 total cases, the circumstances surrounding this outbreak presented more problems than the first. Most of the deaths were elderly patients or cases suffering comorbidities which worsened the outcome. This was likely a consequence of COVID-19 transmission to other patients in hospital systems. Re-opening borders following the first wave inevitably elevated Vietnam’s risk for a new outbreak of imported cases. Indefinitely restricting travel to other countries also posed economic consequences for Vietnam, which means ongoing testing and monitoring is a crucial factor in estimating risk of outbreak for different provinces. In addition to continuous testing, control of infection clusters also depended on the population’s compliance to social distancing. Capacities for quarantine, contact tracing, and mass testing varied between provinces; to handle weaknesses in local health systems, the government mobilized resources on a grassroots level to minimize strain. Despite the challenges each wave of COVID-19 brought, Vietnam was recognized for its strict rapid-response strategy and ranks number 1 globally alongside Laos by the University of Oxford’s COVID-19 Government Response Tracker, cementing the importance of a proactive government cooperating with its healthcare system.
The outcomes for these countries seem to support three critical factors for elimination to be effective: 1) health surveillance systems with the infrastructure capable of handling a rise in case volumes and contact tracing; 2) a country’s public health system must have effective interventions for all populations and support vulnerable, marginalized groups; and 3) an adaptability to adjust usage of resources as the outbreak situation changes. New Zealand, Taiwan, and Vietnam all demonstrated active political commitment working in tandem with a cooperative and trusting public. Overall, the ‘zero-COVID’ strategy has done well for these countries in greatly reducing case numbers and mortality to have minimal impacts; the economic impact of closures also appeared to be minimized. If we refer to these countries and similar nations’ use of elimination as case studies, the new elimination approach might become standard procedure for when a new contagion inevitably appears.
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