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Evidence Check

A rapid review outlining the available evidence on a discrete topic or question relating to the current COVID-19 pandemic. Evidence includes grey and peer review literature. View all Evidence Checks by date of publication.

Emerging evidence about COVID-19 vaccines

Added: 25 Jan 2021

What evidence is emerging about the efficacy, safety and rollout of COVID-19 vaccines?
  • There are four main vaccine types: whole virus, protein subunit, nucleic acid and viral vector
  • To date, nine vaccines have been registered in one or more countries
  • Results of phase 3 trials have been published for two messenger RNA (mRNA) vaccines (Pfizer/BioNTech and Moderna) and one vector vaccine (Oxford/Astra-Zeneca).
  • There are different potential clinical endpoints for evaluating the efficacy of COVID-19 vaccines. These include SARS-CoV-2 infection, asymptomatic infection, COVID-19 (symptomatic disease), severe COVID-19, mortality and transmission.
  • In the published phase 3 studies to date, efficacy is reported using symptomatic disease as the primary endpoint.
  • Vaccine efficacy (using symptomatic disease as the primary endpoint) was 95.0% for the Pfizer/BioNTech vaccine, 94.1% for the Moderna vaccine and 70.4% for the Oxford/Astra-Zeneca vaccine (varying from 62.1% to 90.0% based on the schedule used).
  • All three vaccines had an acceptable safety profile.
  • It is not yet clear what vaccine efficacies and coverage levels will achieve herd immunity.
  • According to the World Health Organization, the vaccines that have been approved to date should provide protection against emerging SARS-CoV-2 variants, as they elicit a broad immune response. Evidence is however emerging that there may be some immune escape
  • The evidence on efficacy and effectiveness of COVID-19 vaccines is rapidly emerging. To date, there is limited to no information on efficacy re SARS-CoV-2 infection or asymptomatic infection, mortality and transmission. Nor is there published evidence on the impact of changes to dosage schedules, the duration of protection, different vaccination strategies or mixed vaccine use.

SARS-CoV-2 variants

Added: 20 Jan 2021

What is the evidence of the new SARS-CoV-2 variants (20B/501Y.V1 and 20C/501Y.V2) in terms of their infectivity, virulence, and effectiveness of the current vaccines?
  • Viruses constantly change through mutation and over time new variants of a virus are expected to occur.
  • New SARS-CoV-2 variants have recently emerged, most notably in the United Kingdom (UK), known as 20B/501Y.V1, variant of concern (VOC) 202012/01, or B.1.1.7 lineage and in South Africa known as 20C/501Y.V2 or B.1.351 lineage.
  • Other variants have recently emerged in Nigeria and Japan.
  • According to the World Health Organization the vaccines that have been approved should provide protection against variants, as the vaccines elicit a broad immune response.
  • While public health measures such as physical distancing, limitations on large gatherings and masks should remain effective, control of a more transmissible variant will require more widespread adoption of these measures.

Ivermectin and COVID-19

Added: 23 Dec 2020
Updated: 15 Jan 2021

Ivermectin and COVID-19
  • Currently, there are insufficient data to support the use of ivermectin for prophylaxis or treatment of COVID-19. - There was insufficient evidence to include ivermectin in the 17 December 2020 release of the BMJ living systematic review on drug treatments
  • however, three randomised controlled trials will be included in the next update inclusion. - The 17 December 2020 update for the World Health Organization guideline on drugs for COVID-19 does not include ivermectin.
  • While there is evidence of in vitro activity of ivermectin on infected cells, the necessary concentrations for in vivo effect are unlikely to be attainable in humans.
  • The Pan American Health Organisation, the World Health Organization regional office for the Americas, published a report in June 2020 that stated studies on ivermectin were found to have a high risk of bias, very low certainty of the evidence, and that the existing evidence is insufficient to draw a conclusion on benefits and harm.
  • While a more recent systematic review found a statistically significant effect on mortality and symptoms, the quality of evidence was very low.
  • There is continuing interest particularly in the Americas, India, and Bangladesh in the use of ivermectin prophylactically and therapeutically.
  • Emerging evidence from randomised controlled trials is mixed. - High dose ivermectin showed no reduction in viral load at day five. - Patients receiving ivermectin plus standard care reported improvement in laboratory and severity parameters. - A phase 2 clinical trial showed a decrease in hospitalisation and duration of low oxygen saturation with adjunct ivermectin treatment. - A three-arm randomised controlled trial of a five-day course of ivermectin reported that changes in patient symptoms were not clinically significant compared with placebo.
  • In the USA, the Front Line COVID-19 Critical Care Alliance advocates for further study of ivermectin. However, the US Food and Drug Administration released advice on 16 December 2020 that ivermectin is not approved for the prevention or treatment of COVID-19.

Aged care facilities and COVID-19

Added: 10 Dec 2020

What are different jurisdictions doing to manage COVID-19 in aged care facilities?
What evidence is there about best practice in preventing and managing COVID-19 infections?
  • More than 71,000 people live in residential aged care facilities in NSW and to date, there have been 61 COVID-19 cases in these facilities and 29 deaths. Incidence is low in comparison with most other jurisdictions.
  • Of the total 52 COVID-19 deaths in NSW, 56% (n=29) occurred in residential aged care facilities. Available international comparisons on this indicator range from 0% in Hong Kong to 82% in Canada.
  • An international review identified emerging evidence on measures to contain COVID-19 outbreaks in care homes. - Early detection and rapid response after detection of index case - Systematic testing of all residents and staff (due to the high prevalence of asymptomatic and pre-symptomatic cases that would not be detected by symptom screening or one-off testing) - Moving high-risk contacts of cases out of the facility - Isolating cases by removing them from the facility or creating separate wards within the facility.
  • A systematic review and expert consensus from the European Geriatric Medicine Society advocates for universal adoption of standards of medical care in nursing homes.
  • Digital technologies have shown some promise in aged care facilities for contact tracing and early identification and remote monitoring.
  • Case studies report effective collaborations between a hospital and nursing homes in Canada and the US and a three phase system response (initial, delayed, surge) in Washington State.
  • A number of studies, predominantly from the US, found an association between COVID-19 incidence and staffing levels and ratios.
  • In North American studies, the odds of a COVID-19 outbreak was associated with the incidence of disease in the region surrounding a facility, the number of residents, older design standards of the home, and the proportion of African American residents, but not profit status.

Deployment and vaccination plan for COVID-19

Added: 9 Dec 2020

What is the current guidance on developing a vaccination plan for COVID-19?
  • The World Health Organization (WHO) has released an interim guidance on developing a national deployment and vaccination plan for COVID-19 vaccines. This evidence brief provides a summary of this document, with supplementary information specific to the Australian context.
  • As of 2 December 2020, on the National Centre for Immunisation Research and Surveillance website, there were 213 vaccine candidates including 45 vaccine candidates in human clinical trials and 11 vaccine candidates in phase III clinical trials.
  • It is anticipated that most SARS-CoV-2 vaccines will require at least two doses for optimal immunogenicity. Storage and distribution temperature will likely be +2°C to +8°C for most vaccines but may require an ultra-cold chain of -20°C to -80°C storage for certain products.
  • The COVID-19 vaccine products are likely to have varying vaccine characteristics and presentations and will require different administration techniques.
  • The Australian government has established vaccination policy and secured agreements for the supply of four promising COVID-19 vaccines, provided they prove to be safe and effective.
  • Early studies looking at hypothetical COVID-19 vaccine acceptance amongst Australians estimated that approximately 4.9% would refuse and 9.4% are indifferent about receiving a COVID-19 vaccine. Inadequate health literacy and lower education level were associated with vaccine reluctance.

Routine border screening evidence check

Added: 7 Dec 2020

What is the evidence or existing policy for routine asymptomatic screening for COVID-19 in exposed workers at border settings (such as airports, seaports, hotel quarantine)?
Is there evidence for which workers should be screened (such as all staff, cleaning staff, compliance staff, security, catering, health)?
What is the most effective frequency of screening?
What is the most effective type of screening (such as saliva, nasopharyngeal swabs, serology)?
  • No studies were identified in the peer reviewed literature for routine asymptomatic screening for COVID-19 in exposed workers at border settings. Many articles on asymptomatic screening for travellers were identified, but not included in this review.
  • Many documents outline action plans, including monitoring and reporting of COVID-19 symptoms of workers and encouraging testing if workers have symptoms, without mentioning routine testing.
  • In Australia, hotel quarantine has been identified as a major risk for the reintroduction of COVID-19 to Australia and as a result, state health authorities have introduced weekly testing of quarantine staff.
  • Asymptomatic workers at Western Australia's borders and in quarantine hotels will be able to take up weekly COVID-19 testing (from 11 September until 30 November). This includes testing staff at: - quarantine hotels including
  • hotel employees, security staff working at the hotel, health staff, drivers of transport of quarantine guests, WA police and others such as the defence force - Perth airport including
  • workers on site, airport or airline staff, WA police, security, federal agencies, drivers of hotel quarantine buses - sea ports and border crossings including
  • anyone involved with close contact of people arriving from overseas or interstate.
  • In New Zealand, an asymptomatic testing program for higher-risk workers includes: - managed quarantine facilities and transport (testing once every 7 days) - managed isolation facilities and transport (testing once every 14 days) - Ports of Auckland, Port of Tauranga and Auckland International Airport (testing once every 14 days) - people who work in managed isolation or quarantine facilities, including those who drive people entering the country from the airport to the facilities, border workers in customs, biosecurity, immigration and aviation security at airports, people who clean in areas used by arriving travellers, or who clean the aircraft, and people working in airside services such as food-halls where people in transit may be waiting. Border workers at maritime ports such as ship pilots, stevedores and those providing seafarer welfare support as well as people working in customs, immigration and public health at maritime ports and air crew.
  • In Singapore, staff at Changi Airport who come into close contact with passengers are tested for COVID-19 every two weeks.
  • The United States - Department of Transportation have guidance for air carriers and staff based around health monitoring and screening for symptoms at the start of duty - Delta airlines announced it will start offering rapid response COVID-19 tests to its flight attendants. The optional tests will be performed by a clinician via nasal swab with results taking fewer than 15 minutes (news article) - In high-density critical infrastructure workplaces, the Centers for Disease Control and Prevention recommend a risk-based approach to testing co-workers of a person with confirmed COVID-19. General practices should include pre-screening (temperature and symptom assessment) and regular monitoring of symptoms.

High-risk settings for transmission of COVID-19 evidence check

Added: 18 Nov 2020

What is the evidence for transmission of COVID-19 in different settings, and which settings are high-risk?
  • A statement from the Australian Health Protection Principal Committee (AHPPC) describes several very high-risk environments including nightclubs, dance venues, and large unstructured outdoor events such as music festivals, food festivals, school guardians’ festivals, carnivals, community sporting events and other non-ticketed spectator events. These events are high risk due to factors such as but not limited to large numbers, close proximity and mixing between groups of people.
  • Healthcare and residential aged care settings are known to be high risk but are excluded from this review
  • A systematic review identified 22 types of settings, predominantly indoor settings that result in SARS-CoV-2 transmission clusters. Risk was classified based on the number of infections per cluster or the proportion of people in that setting who became infected. Most clusters involved fewer than 100 cases, with the exceptions being in large religious gatherings, food processing plants, schools, shopping, and large co-habiting settings (worker dormitories, prisons and ships). Other settings with examples of clusters between 50–100 cases in size were weddings, sporting events, bars, shops and workplaces.
  • A rapid review, prepared by The National Collaboration Centre for Methods and Tools looking at risk of COVID-19 transmission across different indoor settings in the community, reported that households and shared accommodations (e.g. cruise ships) thus far appear to be the most prevalent locations for infection clusters. In settings involving indoor physical activity (gyms and fitness classes), attack rates are highly variable and range from 7.3-26.3%. Transmission appeared to occur more commonly from fitness instructors to participants. Furthermore, modelling studies estimated risk level for different indoor scenarios found ventilation, reducing crowd size, wearing a mask and physical distancing may decrease transmission risk.
  • Most evidence were from single case reports. For many settings, there were insufficient data to determine whether the settings are categorically high risk. Studies were mostly descriptive, with some concluding that transmission was likely facilitated by close proximity. Indoor settings featured in the literature included: Establishments providing accommodation: homeless shelters, prisons, work dormitories, cruise ships Occupational settings: military, factories, offices, call centres and schools. Social/recreational settings: family and religious gatherings, shopping centres, choir, restaurants, fitness centres and aircrafts.

Wastewater surveillance for COVID-19 evidence check

Added: 11 Nov 2020

What is the evidence for monitoring wastewater as a surveillance strategy for COVID-19?
  • The presence of SARS-CoV-2 in the faeces of infected patients and wastewater has drawn attention to the use of wastewater as an epidemiological tool. Wastewater surveillance of COVID-19 can be an efficient, cost-effective way to survey transmission dynamics of communities as a complementary approach to assessing the prevalence of COVID-19 in a community.
  • SARS-CoV-2 has been detected in wastewater samples from many regions around the world including
  • Australia, Spain, Italy, Netherlands, China, the United States of America, Germany, Japan, India, Czech Republic, Brazil and Ecuador.
  • Often in these reports wastewater samples tested positive before, at the same time, or soon after positive COVID-19 cases were reported in the respective areas. In one study, the viral titers observed were significantly higher than expected based on clinically confirmed cases.
  • While the majority of studies detect positive SARS-CoV-2 in raw wastewater, there have been some positive tests in treated wastewater. This needs to be balanced against studies that did not detect positive SARS-CoV-2 in treated wastewater.
  • The World Health Organization outlines major potential use cases for environmental surveillance for SARS-CoV-2 including: early warning, detection in locations with limited clinical surveillance, monitoring circulation of SARS-CoV-2 and research. Considerations outlined by the World Health Organization for implementing environmental surveillance include: representativeness, coordination, cost-effectiveness, ethical and legal considerations and quality assurance.
  • In Australia, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) has a method for monitoring sewage for early detection of COVID-19 outbreaks over 14 days, from people being exposed to SARS-CoV-2, wastewater samples collected and tested, reporting to public health officials, through to clinical nasal swab tests for people who begin to show symptoms.

Daily Evidence Digest

Rapid evidence checks are based on a simplified review method and may not be entirely exhaustive, but aim to provide a balanced assessment of what is already known about a specific problem or issue. This brief has not been peer-reviewed and should not be a substitute for individual clinical judgement, nor is it an endorsed position of NSW Health.

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