Household secondary infection rate only 16%: study

Around one in six people sharing a house with an infected person will get COVID-19.

Welcome to The Medical Republic’s COVID Catch-Up.

It’s the day’s COVID-19 news in one convenient post. Email bianca@biancanogrady.com with any tips, comments or feedback.

15 December

• Secondary attack rate of COVID-19 in households around 16%, analysis shows.
• Controlling the pandemic will take more than just a vaccine, Australian experts say.
• Pfizer/BioNTech vaccine can be used in people previously infected with SARS-CoV-2.
• The challenges of contact tracing around the world.
• The latest confirmed COVID-19 infection numbers from around Australia.

• Around one in six people sharing a house with an infected person will get COVID-19, according to a systematic review and meta-analysis.
  A paper published in JAMA Network Open reviewed 54 studies involving more than 77,000 participants, and found that mean secondary attack rate for households was 16.4%, and for family contacts it was 17.4%.
  When the index case was aged under 18 years, the secondary attack rate was just 0.5%, and asymptomatic or presymptomatic index cases had a secondary attack rate of 0.7%, although the authors commented there were relatively few studies of these cases.
  Spouses of infected people had the highest infection risk, followed by other family members, and infection risk increased with increasing contact.
  “Prevention strategies, such as increased mask-wearing at home, improved ventilation, voluntary isolation at external facilities, and targeted antiviral prophylaxis, should be further explored,” the authors wrote.
• Even an effective COVID-19 vaccine is unlikely to be a silver bullet for the pandemic, and the most likely scenario for 2021 will be a combination of vaccination, testing, contact tracing, isolation and other public health approaches including physical distancing, experts say.
  The Australian Academy of Health and Medical Sciences has issued a report on Australia’s path through the COVID-19 pandemic, written by some of Australia’s leading medical researchers, which calls for “suite of strong public health and policy measures from federal, state and territory governments”.
  While acknowledging the encouraging results of vaccine trials so far, showing up to 90% efficacy, the expert committee also stressed the need for new treatments for COVID-19, faster and more accessible diagnostic tests, and better management of the ‘social and health inequalities’ that have seen some groups suffer disproportionately from the pandemic.
• The Pfizer/BioNTech COVID-19 vaccine can be given to individuals who have had prior suspected or confirmed SARS-CoV-2 infection, but should be delayed for at least 90 days in people who have received either convalescent plasma or monoclonal antibody treatment for COVID-19, says the US CDC.
  The CDC’s Advisory Committee on Immunization Practices published advice on the two-dose vaccine, citing trial evidence suggesting the vaccine was safe and ‘likely efficacious’ in people who had had symptomatic or asymptomatic COVID-19.
  While data on how the vaccine performs in individuals who are immunocompromised, taking immunosuppressive medication or have HIV is not yet available, the advice is that these individuals can be vaccinated unless contraindicated.
  The vaccine has also not been tested in pregnant women, so the CDC advised that pregnant women who are in a group recommended for vaccination – such as healthcare workers – should consult a doctor about whether to undergo vaccination (although doesn’t expand on what doctors should tell pregnant women).
• Contact tracing is partly credited with helping Australia get the pandemic under control, and its weaknesses in Victoria have been blamed for the second wave, but how are other countries around the world handling this challenge?
  A Nature news feature explores some of the techniques being used to determine where infected individuals have travelled and who they have encountered who might have been exposed to the virus. South Korea has made use of credit card and mobile phone data, while Vietnam has even tapped into people’s social media posts to fill in gaps in contact tracing efforts.
  It also looks at the apps that are used, why trust is so important for contact tracing efforts, and why some affluent nations have struggled to marshal the large workforce needed for effective contact tracing.
• Here are the latest confirmed COVID-19 infection numbers from around Australia to 9pm Monday:
  National – 28,039 with 908 deaths
  ACT – 117 (0)
  NSW – 4645 (3)
  NT – 64 (1)
  QLD – 1227 (1)
  SA – 563 (1)
  TAS – 234 (0)
  VIC – 20,352 (1)
  WA – 837 (1)