Evidence Check - Epidemiology and transmission

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

Face masks in the community – evidence and international policy during the COVID-19 pandemic

Added: 29 Oct 2021
Updated: 16 Dec 2021

What is the evidence for the effectiveness of face masks in community settings for reducing influenza-like illnesses, including COVID-19?
  • Most systematic reviews report benefits in terms of reduction in incidence, hospitalisation and/or mortality.
  • The efficacy of protection against respiratory viral infections may vary according to the type of mask used.
  • Face masks are often recommended alongside other protective measures including hand hygiene and physical distancing.

Paediatric respiratory infections

Added: 6 Dec 2021

What is the evidence for paediatric respiratory infections after lockdown and school reopening during COVID-19?
  • Countries in both southern and northern hemispheres reported no immediate impact on the incidence of respiratory pathogens following reopening of schools and day care centres. However, some countries such as the U and China reported eran increase in intseasonal RSV activity.
  • There is a concern that due to the reduced circulation of RSV during the winter months of 2020/21, older infants and toddlers might now be at increased risk of severe RSV-associated illness since they may not have had typical levels of exposure to RSV during the past 15 months.
  • In several jurisdictions, the routine use of influenza vaccines and antiviral medications in the prevention and treatment of respiratory infections in children are recommended.

Deep cleans

Added: 19 Apr 2021
Updated: 6 Dec 2021

What is the evidence for fomite transmission and deep cleaning of COVID-19?
  • In February 2020, the World Health Organisation (WHO) noted fomites as a potential route ofCOVID-19 transmission.1 However, in July 2020, an update noted that despite consistent evidence of SARS-CoV-2 RNA on certain surfaces, there is no direct evidence of fomitetransmission.
  • Despite the low risk of fomite transmission, there continues to be significant investment in deep-cleaning and disinfection to reduce potential surface contamination . A Nature perspective in January 2021 questioned the value of this.

Hospitalisation and ICU admission relative risk

Added: 4 Nov 2021

What is the evidence for the relative risk of hospitalisation and ICU admission for vaccinated versus unvaccinated people?
  • The effectiveness of vaccines can be assessed by comparing the risk of hospitalisation or ICU admission among vaccinated versus unvaccinated people.
  • Data from NSW has shown that the majority of COVID-19 patients in intensive care units are unvaccinated or only partially vaccinated.
  • In patients 16 years and older, there was a 24-fold higher risk of hospitalisation and a 46-fold higher risk of ICU admission in unvaccinated people compared to vaccinated people. The difference increases in the 40-59 years age group, with a 47-fold higher risk of hospitalisation and a 70-fold higher risk of ICU admission.

De-isolation and risk of transmission

Added: 29 Oct 2021

What is the evidence for de-isolation and the risk of COVID-19 transmission?
  • The likelihood of shedding infectious virus beyond 10 days following symptom onset is very low in COVID-19 patients with mild to moderate disease and remains low in severely ill COVID-19 patients.
  • Generally, 10 days passed since COVID-19 symptoms or date of first positive test is the timeframe from discontinuation of transmission-based precautions, including isolation. In Australia, the Communicable Diseases Network Australia uses 14 days passed as the criteria.
  • Extended isolation and precautions for up to 20 days after symptom onset may be warranted in some cases.

COVID-19 vaccine booster shots

Added: 12 Oct 2021

Evidence check on COVID-19 vaccine booster shots
  • While there is evidence of a reduction, or waning, of serum antibodies to SARS-CoV-2 post-vaccination, vaccines continue to provide effective protection against symptomatic and severe disease and death
  • The effect of waning immunity is still emerging internationally. Some jurisdictions such as Israel, have seen high rates of hospitalisation concurrent with waning immunity, while others such as the United Kingdom (UK), have seen a decline in hospitalisations and deaths despite decreasing antibody levels.
  • This has raised questions about the need for booster doses of vaccine.

Therapeutic sessions and personal protective equipment

Added: 30 Sep 2021

How does the wearing of personal protective equipment (PPE) impact on therapeutic sessions with adults and children who have experienced domestic or family violence, sexual assault, abuse or neglect?
  • There is limited evidence on how the wearing of PPE impacts on therapeutic sessions with adults and children who have experienced domestic or family violence, sexual assault, abuse or neglect.
  • Most of the literature focuses on face masks rather than PPE.
  • One peer-reviewed qualitative study of three cases from the UK found the wearing of face coverings to be a potentially significant stressor. For one individual, wearing a facemask felt like a hand covering their mouth.1 Another case study reported that mandated face masking in public may exacerbate post-traumatic stress disorder symptoms in victims who were assaulted by masked perpetrators or had their mouth and nose covered by the perpetrator during the assault.
  • Many experiences have been described in the grey literature including newsletters and blogs. Overall, the themes described are: -Face masks can make it difficult for others to hear, appear threatening to some clients, and make it difficult to fully express facial emotions. -Masks can trigger old trauma for adults and children who have experienced violence, assault, abuse or neglect. -Virtual sessions can assist in face-to-face therapy. -Clinicians and clients adapted quickly to mask wearing.
  • Coping strategies to assist those who have experienced trauma in complying with face mask requirements include: -flash cards -grounding techniques that use sight, smell, sound, and taste -cognitive techniques.
  • The British Psychological Society has developed a guide for practising psychologists which includes suggestions to help overcome PPE challenges, such as: -creating new positive associations with PPE -printing photo of face on A4 paper to attach to torso with name badge -practising a range of different interactional techniques, such as exaggerating movement, slowing down talk and smiling with eyes.

Period of isolation relevant to vaccination status

Added: 29 Sep 2021

Evidence check on period of isolation relevant to vaccination status
  • Throughout the COVID-19 pandemic, public health measures such as quarantine, lockdown, isolation, social distancing and mask wearing have been effective in reducing the transmission of COVID-19.
  • COVID-19 vaccines have been shown to be highly effective in providing protection against symptomatic and severe COVID-19. Vaccines have also been shown to reduce the chance of onward transmission by 40 to 50%.
  • Additionally, for people who are infected with the Delta variant, vaccinated individuals are likely to experience faster drop in viral loads after day seven of diagnosis compared to unvaccinated individuals and likely to spread the virus for a lesser time.
  • As the pandemic progresses and more people are vaccinated, jurisdictions around the world are considering the impact of vaccination on other public health measures. Some jurisdictions have waived the requirement for self-isolation for fully vaccinated individuals that were identified as close contacts. This is on condition that they either don’t have symptoms or get tested at various points in time after exposure.

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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