Evidence Check - Epidemiology and transmission

Community transmission and hospital infection, stages of pandemic, immunity, vaccination.

Influenza and seasonal prophylaxis with oseltamivir

Added: 17 Jun 2022

What is the place or evidence for seasonal influenza prophylaxis (such as taking oseltamivir for 10 to 12 weeks continuously) in healthcare and aged care settings?
What is the place or evidence for seasonal influenza prophylaxis in high-risk patients who have or require frequent contact with healthcare facilities (for example, dialysis patients)?
  • No systematic reviews have been conducted on this topic since 2013. Three older reviews note that there is some evidence for the effectiveness of oseltamivir as seasonal prophylaxis in at-risk adults. However, the quality of those studies was evaluated as low. Notably, many older studies and reviews on this topic have been criticised due to their heavy involvement of pharmaceutical sponsors and lack of replication or transparent data.
  • In adults, very few studies provide real-life evidence for the use of oseltamivir for seasonal prophylaxis in at-risk adult populations. The few that do exist found a positive benefit in reducing influenza incidence and secondary complications in long-term care residents, dialysis and transplant patients.
  • In children and adolescents who are immunocompromised, unvaccinated or at risk of influenza complications, there is stronger and more recent evidence to recommended seasonal oseltamivir.

Emerging variants

Added: 13 May 2022

What is the available evidence for emerging variants?
  • The World Health Organization is monitoring BA.1, BA.2, BA.3, BA.4, BA.5 and descendent lineages and BA.1/BA.2 circulating recombinant forms such as XE under Omicron, however, the World Health Organization advises that public health authorities should monitor descendant lineages as distinct lineages.
  • Variants under monitoring listed by the World Health Organization include B.1.640 and XD recombinant (Delta AY.4 and Omicron BA.1).
  • Three Omicron sublineages BA.4, BA.5 and BA.2.12.1 have acquired additional mutations that may impact their characteristics (BA.4 and BA.5 have the del69/70, L452R and F486V mutations, BA.2.12.1 has the L452Q and S704L mutations).

COVID-19 pandemic and influenza

Added: 14 Apr 2022

What is the evidence for COVID-19 pandemic and influenza?
  • During the COVID-19 pandemic many jurisdictions have seen a sharp decline in influenza circulation, especially during the typical flu season, compared to pre-pandemic periods.
  • Vaccination remains one of the most effective measures to prevent influenza outbreaks, and is seen as critically important following relaxation of COVID-19 restrictions.
  • Australian Technical Advisory Group on Immunisation advises that influenza vaccines can be co-administered (i.e. on the same day) with the COVID-19 vaccines.

COVID-19 vaccines in Australia

Added: 19 Aug 2021
Updated: 18 Mar 2022

What is the evidence on COVID-19 vaccines in Australia?
  • Internationally as of 16 March 2022, 35 vaccines are approved and 11.04 billion doses have been administered.
  • In Australia, four vaccines have been approved for use - Comirnaty (Pfizer), Spikevax (Moderna), Vaxzevria (AstraZeneca), and Nuvaxovid (Novavax). As of 13 March 2022, approximately 55.1 million doses have been administered.
  • All vaccines that are approved for use have strong safety profiles and benefit to risk ratios.

Omicron (BA.2 sub-lineage)

Added: 11 Feb 2022
Updated: 18 Mar 2022

What is the available evidence for the BA.2 sub-lineage of the Omicron variant of concern?
  • Omicron includes four Pango lineages: the parental B.1.1.529 and the descendent lineages BA.1, BA.2 and BA.3. WHO is monitoring all variants under ‘Omicron’.
  • Properties of BA.2 are under investigation but remain unclear. WHO recommends that investigations into the characteristics of BA.2, including immune escape properties and virulence, should be prioritised independently (and comparatively) to BA.1.
  • The UK Health Security Agency (UKHSA) Variant Technical Group designated BA.2 as a ‘variant under investigation’ on 19 January 2022.

Mask type for COVID-19 positive wearer

Added: 11 Feb 2022

What is the evidence for different mask types for COVID-19 positive wearers?
  • Most of the available literature on different mask types looks at the prevention of COVID-19 infection and is not specifically carried out in COVID-19 positive people.
  • In experimental studies on COVID-19 positive patients, surgical masks have been shown to be less effective in filtering viral particles compared with N95 masks.
  • Australian Government guidance on personal protective equipment in hospitals states that patients with acute respiratory symptoms or confirmed or potential COVID-19 wear a surgical mask. TheWorld Health Organization suggests disposable medical masks be worn by people who have recently tested positive for COVID-19.

Paediatrics and COVID-19 reporting rates and differences

Added: 27 Jan 2022

How are paediatric patients with COVID-19 reported, and what are the differences in rates and severity with Omicron?
  • In Australia, COVID-19 statistics provided by federal, and most state governments, report on distribution of cases by age groups, with children and young people split into age groups of 0-9 and 10-19 years. Age groupings vary across countries.
  • Reports about the Omicron variant point to a rise in the overall counts of new infections and hospitalisations among children, especially children under the age of five.
  • Reports from the United States, South Africa, and UK indicated that children admitted to hospitals during the Omicron variant wave with COVID-19 had lower risk of severe clinical outcomes.

Omicron (B.1.1.529) variant

Added: 10 Dec 2021
Updated: 27 Jan 2022

What is the evidence for the variant of concern Omicron (B.1.1.529) in terms of transmissibility, disease severity, COVID-19 treatments and vaccines?
  • Omicron (B.1.1.529) was designated a variant of concern by the World Health Organization on 26 November 2021.
  • It was first reported to WHO from South Africa on 24 November 2021.
  • It has 50 mutations, including 26-32 mutations on its spike protein.

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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