COVID and pandemic preparedness
Associate Professor James Trauer, Head of the Epidemiological Modelling Unit for the School of Public Health and Preventive Medicine says,
“Vaccination remains our most important defence against Covid, even though the virus shouldn’t ruin Christmas this year. We are currently experiencing a significant wave of transmission in Australia. Testing has declined markedly and the daily number of cases doesn’t provide a clear picture of the extent of transmission any more. However, other data sources still give us a good sense. For example, wastewater surveillance and hospital admissions show a marked increase in infections over the last few months.
“Overall, the severity of Covid cases has decreased, with fewer people admitted to ICU than in previous years. This is attributable to high levels of population immunity, which is contributed to by both natural immunity (from past infection) and vaccination-derived immunity.
“Covid is now an ‘endemic’ infection, meaning that the infection cannot be eliminated and transmission occurs continuously. When immunity after infection is short-lived, endemic transmission occurs in peaks and troughs as immunity from previous waves fades. This is an expected feature of endemic Covid.
“The emergence of new variants is also contributing to these ebbs and flows. Although a few current variants are being closely watched, none of the currently circulating strains seem to cause more severe disease than the preceding strains. Because new variants are contributing significantly to each wave of infection, it is more difficult than ever before to predict when they will peak.
“Because immunity after infection is so short-lived, reducing transmission in the short-term will have little effect on the number of times people get infected with Covid over the course of several years. Therefore, our most important protection against the effects of Covid is immunity, which can be enhanced through vaccination.“As per ATAGI’s recommendations, this is appropriately focused on the most vulnerable to severe outcomes, particularly those aged over 65 or those with risk factors (and especially those aged over 75). Anyone who meets ATAGI’s current recommendations for receiving a booster vaccine should strongly consider this. This is particularly relevant as the recently ATAGI-approved monovalent vaccines become available, which induce stronger immunity against the current circulating variants.
“In addition to vaccination, taking precautions when visiting persons at high risk of severe outcomes (e.g. visiting aged care facilities) remains important. This includes testing in advance and wearing face masks during such interactions. However, these interventions will have a minimal effect on the trajectory of the current wave. Persons at risk of severe disease should also consider testing to ensure that antiviral medications can be provided as soon as possible after symptoms of Covid occur.”