Nimbus variant spikes in US: How long does Covid-19 last?

As the world adapts to living with coronavirus, one common question persists: How long does Covid-19 last? Typically, the duration of a Covid-19 infection ranges from a few days to several weeks, depending on an individual’s health and the severity of the infection. With the emergence of new variants, specifically the recently dominant strain known as NB.1.8.1—or Nimbus— in the US, it is essential to understand how these changes might impact the duration and symptoms of the illness.

Nimbus has quickly established itself as the leading strain of SARS-CoV-2 in the US, accounting for an estimated 43 percent of Covid-19 infections as of June 2025, according to the Centres for Disease Control and Prevention. First detected in March, this variant is a mutated form of the Nimbus subvariant and has led to alarming symptoms, including what is being referred to as “razor blade throat“.

Nimbus was first detected in the US through airport screenings and has since spread to at least 28 states, according to the Global Initiative on Sharing All Influenza Data (GISAID) database. The World Health Organisation designated NB.1.8.1 as a “variant under monitoring” due to its rapid global transmission, however it is not riskier than other strains.

According to cardiac anesthesiologist Dr Jagadish Hiremath, as per reports, most cases appear to be mild to moderate in severity. Based on current observations, the duration of symptoms typically lasts around five to seven days for those who are otherwise healthy and vaccinated. Individuals often begin to feel better by the end of the first week. However, some residual fatigue or mild symptoms, such as a lingering cough, may persist for a slightly more extended period.

Covid-19 duration symptoms: What do we know?

The duration of the Covid-19 infection can vary depending on several factors, including the individual’s health, vaccination status, and the specific variant of the virus involved.

• Common duration: For many, Covid-19 presents mild to moderate symptoms similar to those of a common cold or flu, often lasting about a week, typically around 5 to 7 days. However, in some instances, Covid-19 duration can linger for weeks or even months, especially in individuals with pre-existing conditions or those who are older.
• Long Covid: There is a possibility of experiencing long Covid, where symptoms persist for extended periods. These symptoms include fatigue, brain fog, and respiratory issues, which may last for several months.

Understanding your Covid-19 duration symptoms can help manage expectations and inform decisions about care. Typically, mild cases resolve within one to two weeks, while moderate to severe cases may take longer to resolve, sometimes exceeding two weeks.

The impact of the Nimbus variant

The rise of the NB.1.8.1 variant poses particular concerns due to its high transmissibility. CDC data show that while Covid-19 duration remains relatively stable, the emergence of Nimbus cases has led experts to brace for potential increases in cases throughout the summer, a trend observed in previous years. As of June 21 2025, the national test positivity rate was around 3 percent, reflecting a slight increase, while wastewater surveillance indicates Covid-19 duration levels are classified as medium, per the CDC.

For people who are immunocompromised, elderly, or have underlying health conditions, the illness may last longer, and recovery may take more time. In such cases, Dr Hiremath advises careful monitoring.

Is Nimbus more transmissible?

The viral landscape is continually evolving, especially in the context of the covid-19 pandemic, which has persisted for over three years. Variants like Nimbus often have mutations that may enhance their ability to infect. Derived from the recombinant Omicron variant XDV.1.5.1, Nimbus exhibits several spike protein mutations, which have led to speculation about its potential to spread more rapidly than previous strains.

It is also worth noting that even with milder strains, the virus remains contagious. People are generally considered most infectious from one to two days before symptoms begin, up to about five days after. Therefore, taking precautions such as wearing masks and maintaining social distancing during this period remains essential, says Dr Hiremath. While the strain may cause less severe illness overall, staying up to date with vaccinations and seeking medical advice when symptoms persist or worsen remains the best approach for protection and recovery.

Recognising the symptoms of Nimbus

Understanding the symptoms associated with Nimbus is crucial for recognising the illness early on. Symptoms reported so far closely resemble those of Omicron infections, including:

• Sore “razor blade” throat
• Cough
• Runny nose or congestion
• Shortness of breath
• Fever or chills
• Headaches and body aches
• Fatigue
• Loss of taste or smell

The Covid-19 duration symptoms can vary, but they often last for about 5 to 14 days. A distinctive sore throat symptom, characterised as a “razor blade throat,” has become particularly associated with this strain.

Vaccination and protection

Vaccination remains a cornerstone for reducing the severity of covid-19 duration, including the NB.1.8.1 variant.

• Vaccine recommendations: The CDC recommends that most adults, especially those in high-risk groups, receive vaccinations or boosters if they haven’t been vaccinated recently.
• Vaccine efficacy: Current vaccines are expected to be effective against the Nimbus variant, and upcoming vaccines targeting the LP.8.1 strain are anticipated for release in the fall. As the covid-19 pandemic has persisted for several years now, it remains crucial to stay updated on vaccine developments.

Managing Covid-19 today

To navigate the complexities presented by the ongoing pandemic and emerging variants, individuals should:

• Test when symptomatic: Stay vigilant and test if covid-19 symptoms appear.
• Isolate if infected: Follow the guidelines to prevent the spread of the virus.
• Wear masks: Particularly in crowded indoor settings where the risk of transmission is higher.
• Practice social distancing: Maintain distance from others in public places.