Why are cases still high as the weather gets warmer? Does temperature affect the activity of the virus?

It is the season of spring again, when flowers bloom in full bloom. In this most vibrant season of the year, many people are confined to their homes due to the epidemic. Many people find it strange. Isn't it true that the higher the temperature, the lower the activity of the virus? The flowers are blooming, so why is the virus still so active? What is going on? Don't worry, let's talk about it today.

In fact, this problem is mainly about temperature and degree. We analyze it from three aspects, and see the following.

01. Does temperature affect virus activity?

Does temperature have an effect on virus activity? The answer is yes.

Viruses are afraid of heat but not cold. This is an important characteristic of viruses. This is true for all viruses, and even for all living things. The reason behind this is from a biochemical perspective and has nothing to do with what kind of life you are.

Taking a simple virus as an example, the virus is essentially still a combination of organic matter, consisting of nucleic acid and protein.

These ingredients will become less active or even inactivated at high temperatures.

For example, proteins usually require higher-level structures to function, but under high temperatures, these higher-level structures will be broken and then denatured.

You can understand this as boiling eggs, so our daily disinfection method is to steam and cook at high temperature. In fact, with current science and technology, we cannot even restore proteins that have been denatured at high temperatures, because protein folding is a very complex biological process.

If the connection is slightly wrong, the protein will be inactivated. However, at low temperatures, protein nucleic acids are difficult to denature and are easy to preserve, which is why viruses are afraid of heat but not cold.

02. Is the new coronavirus afraid of heat?

I believe many people have been told that the virus is afraid of heat but not cold. However, whether it is delta or omicron, it seems that the situation is still very serious when the temperature rises. Could it be that the virus is not afraid of heat?

But as mentioned above, the virus is still afraid of heat. So, someone will definitely ask, if this is the case, why has the number of new COVID-19 cases not decreased as the temperature has risen, and the epidemic is still so serious? Isn’t the new coronavirus afraid of heat?

This brings us to another question, which is the impact of temperature changes and viruses. Temperature changes can affect virus transmission to a certain extent, and there is a lot of research evidence for this, but it does not mean that the virus will necessarily become weaker when the temperature rises.

On the one hand, our temperature is changing, but it has not risen so drastically as to 100℃, and it has not even reached 56℃, a level that can eliminate the virus to a certain extent.

On the other hand, viruses are not only affected by temperature, but also by the mutation of the virus itself. For example, one of the characteristics of omicron is its increased infectiousness. In this case, perhaps the increase in temperature will slightly reduce its ability to spread, but in the face of the overall mutation of the virus characteristics, this is masked.

Not to mention, population mobility and the situation of susceptible populations are factors that affect transmission.

03. The impact of changes in human body temperature

Does the change in human body temperature have any effect on the virus? This is indeed an important question.

In fact, raising the temperature is an important way for the human body to eliminate foreign pathogens. For example, many people are prone to fever when they are infected. This is actually the process of the human body raising the temperature to kill pathogens (of course, this is not absolute, it may also be a hypothalamic disorder)

Heat, pain, redness and swelling are the four basic response signs of inflammation (calorie, dolor, rubor, tumor).

A review in Nature in 2015 mentioned the immune heat signaling pathway, especially the important role of the cytokine IL-6 and the heat-related adrenaline signaling pathway. Fever is a basic immune response of the body to infection and a strong protective mechanism of the body. A large amount of evidence shows that a [limited] increase in the body's core temperature is beneficial for the treatment of infection. For example, an increase in body temperature is a basic response to infection and immune disease, and it is a protective mechanism of the body formed after millions of years of natural selection. A large amount of evidence shows that during fever caused by many types of infections, the core temperature increases by 1 to 4°C, and the patient's survival rate after infection can be improved. The use of antipyretics to reduce fever will increase the mortality rate of influenza patients by 5%.

However, you overlooked an important point: humans are warm-blooded animals.

For most people, the body generally maintains a relatively constant temperature. In this case, even if the temperature changes, the human body temperature will remain relatively stable.

The impact of air temperature on body temperature fluctuations may not be as great as the temperature difference between day and night.

But then again, drastic temperature fluctuations do affect human immunity.

A typical example is that when the climate fluctuates drastically, the virus tends to experience a wave of rapid spread. The reason behind this is that the drastic climate fluctuations affect people's immunity and make them more susceptible to infection.

In short, these scientific principles often have a broad background and a certain scope. For individuals, the best way is to take good protection.