Dr Ziyad Al-Aly has published some of the most important Long Covid research of the pandemic. His Veterans Affairs studies have highlighted that many risks remain elevated for some people with Long Covid for at least 2 years after initial infection1 and that there appears to be a cumulative health risk from multiple COVID-19 infections2. This last finding is backed by recent data released by Statistics Canada3.

Dr Al-Aly’s latest study looks at the long-term impact of COVID-19 infection and compares it to the harms of influenza4. The new research from Washington University School of Medicine in St Louis and the Veterans Affairs St. Louis Health Care System tracked patients hospitalized for either COVID-19 or seasonal influenza and compared their risk of death, hospital readmission and health problems in a number of organ systems. It made some striking findings:

  1. The highest health risk of both COVID-19 and influenza comes 30 days or later after initial infection. We tend to think of COVID-19 and influenza as acute events, short-term illnesses that we recover from, but in reality, both cause long-haul illness, and the greatest risks come in the weeks and months after initial infection. More than half of death and disability occurred in the months after infection as opposed to the first 30 days. Dr Al-Aly says, “COVID-19 and the flu led to long-term health problems, and the big ah-ha moment was the realization that the magnitude of long-term health loss eclipsed the problems that these patients endured in the early phase of infection. Long COVID is much more of a health problem than COVID, and long flu is much more of a health problem than flu.”
  2. COVID-19 carries a substantially higher health risk than flu. The overall risk and occurrence of death, hospital admissions and loss of health in many organ systems are substantially higher among COVID-19 patients than among those who have had seasonal influenza. Dr Al-Aly says, “The one notable exception is the flu poses higher risks to the pulmonary system than COVID-19. This tells us the flu is truly more of a respiratory virus, like we’ve all thought for the past 100 years. By comparison, COVID-19 is more aggressive and indiscriminate in that it can attack the pulmonary system, but it can also strike any organ system and is more likely to cause fatal or severe conditions involving the heart, brain, kidneys and other organs.”

This chimes with other research, and if you’ve been following the John Snow Project for a while, you’ll know we’ve raised concerns about the systemic effects of COVID-195-7. SARS-CoV-2 is often described as a respiratory illness, but it is better to think of it as a systemic virus that infects the blood8, vasculature9,10, bone marrow11,12, immune cells13-16 and almost every organ17-19, so it is unsurprising that it causes far more widespread harm. It is unquestionably not the flu.

According to the study, COVID-19 patients faced a 50% higher risk of death than those with seasonal influenza, and this corresponded to approximately eight more deaths per 100 people in the COVID-19 group than among those with the flu. COVID-19 resulted in an increased risk of 68% of the health conditions examined across all organ systems, while the flu was associated with elevated risk of 6%, mostly in the respiratory system. For every hundred people in each group, there were 20 more hospital readmissions and nine more ICU admissions in COVID-19 than flu. Dr Al-Aly says, “Before the pandemic, we tended to belittle most viral infections by regarding them as somewhat inconsequential: “You’ll get sick and get over it in a few days.” But we’re discovering that is not everyone’s experience. Some people are ending up with serious long-term health issues. We need to wake up to this reality and stop trivializing viral infections and understand that they are major drivers of chronic diseases.”

This study was conducted during the pre-Delta, Delta, and Omicron dominant periods of the pandemic and the findings hold for all variants, and the researchers found the difference in risk was evident in vaccinated and un-vaccinated individuals.

On X, formerly known as Twitter, Dr Al-Aly said, “The data from the Canadian report are consistent with our results -- both show that reinfection contributes additional risk of Long Covid,”20 and asked, “How many cases of Long Covid could have been prevented if we took reinfection seriously?”21

We echo this question and ask which leaders will step up to protect their populations from the cumulative harm of repeat COVID-19 infections?22 We also echo Dr Al-Aly’s call for more urgent funding to research treatments for the millions of people around the world affected by Long Covid. As the pandemic enters its fifth year, with billions of people experiencing their second, third or more infections, this urgent need is almost certain to increase. As UK Long Covid researchers have said, “The oncoming burden of long COVID faced by patients, health-care providers, governments and economies is so large as to be unfathomable, which is possibly why minimal high-level planning is currently allocated to it.”23

That planning needs to start now.