Common Cold Season Is Here - How to Stay Healthy According to Science?

In this Nexus🔗:

💉 Vaccination: the highest-impact prevention for Flu, RSV and COVID-19
🏃♀️ Daily habits: simple but highly effective when combined
👃 Nose and throat care
💊 Supplements and nutraceuticals: what do clinical trial data say?
❌ Things people do for colds that don’t actually prevent or cure them

Yes, I know, it has been ages since you heard from my Nexus Newsletter. The last quarter has been a period of change and high intensity. But as the flu and common colds season is here, I feel my duty to get back to writing and to share my insights on what works and what doesn’t in preventing common colds or shortening the disease. This article will be slightly irregular from my usual newsletter structure, but I wanted it to be highly practical and useful, providing the tips which can save you from getting sick (and which saved me many times). So get ready to do a summary, as I share insights on vaccination, daily habits, nose and throat care, supplements, methods to shorten symptom duration as well as what doesn’t really work.

Vaccination: the highest-impact prevention for Flu, RSV and COVID-19

Each time I post something about vaccines and vaccination in social media, I get some hate and some unfollows. And I am fine with that. I will say it out loud:

If you don’t believe in science – I cannot help you.

I strongly believe that vaccines is the biggest and greatest invention in the history of medicine, which to date impacted the prolongation of human lifespan the most. Just look at the graph below (1). For most of human history, around half of all children died before reaching puberty, largely due to infectious diseases, inadequate nutrition, and the absence of modern medical care such as vaccines, antibiotics, and sanitation. Can where be a better proof that vaccines are good for us?

So as always, lets look at the clinical trial data:

Influenza. In healthy adults, flu vaccines reduce laboratory-confirmed influenza (risk ratio ~0.41). This means that the risk of getting flu is about 59% lower in the vaccinated group compared with the unvaccinated group. Older adults should consider enhanced formulations (high-dose/adjuvanted) as per local guidance (2).
Respiratory syncytial virus (RSV). Phase-3 randomized clinical trials showed that single-dose RSV vaccines (GSK Arexvy; Pfizer Abrysvo; Moderna mResvia) prevent RSV-associated lower-respiratory disease in adults 60 and older, with efficacy estimates ~63-83% in early follow-up (3).
COVID-19. Vaccines against SARS-CoV-2 significantly reduce the risk of severe disease, hospitalisation and death. For example, the 2024-25 bivalent COVID-19 vaccine showed ~95% efficacy for symptomatic infection in certain populations (4).

Some practical tips about vaccination:

It is best to get vaccinated September-October in the Northern hemisphere, but you can still get your jab any time while viruses circulate.
You can administer the flu, COVID-19 and RSV vaccines at the same visit, different arms. Co-administration is endorsed for eligible adults.
For most inactivated vaccines, you do not need to wait 4 weeks, they can often be given at the same visit or anytime before or after another inactivated or live vaccine. However, for two different live injectable vaccines that are not given on the same day, you should separate them by at least 4 weeks.
Also, make sure you are completely healthy at the time of vaccination. No fever, no runny nose or cough. Otherwise, it might hit you harder.
Don’t have big plans the next day (or in the evening if you had your morning shot). You might not feel your best self for the next 24–36 hours after vaccination. See me smiling in the picture below getting my either Flu or SARS-CoV-2 jab? I was not that smily in the evening and the day after.

Daily habits: simple but highly effective when combined

There are things that we all know, but don’t follow. If you really want to remain healthy during this cold season, the reminders for you are below, even if you’ll say – captain obvious strikes again.

Hand hygiene. Cluster-randomized trials in dorms and community settings show that hand hygiene reduce influenza-like illness during peaks. A large UK randomized trial (PRIMIT) found a ~14% reduction in respiratory infections via a hand-washing program. Use alcohol rubs (or soap and water ≥20 s) after shared surfaces and on return home. A reminder how to properly wash your hands below (5).

Don’t touch your eyes. Ever. Viruses can enter your body not only through the mouth and nose, but also through our eyes, which are connected to our nasal passages by the tear ducts. When you touch your eyes with virus-contaminated fingers, you give pathogens a direct route to the mucous membranes. That’s why it’s important to avoid touching your eyes, especially after handling shared surfaces, and to wash your hands thoroughly (as shown above) before any contact with your face.

Sleep. Sleep is one of the core pillars of our health and immunity. Human viral-challenge studies (where healthy volunteers are deliberately infected with the certain virus) show that short sleep (less than 6–7 h/night) before exposure to a virus triples to quadruples your risk of developing a cold after rhinovirus inoculation (6). Therefore, you should aim for 7-9 h of sleep with consistent timing. In autumn/winter period – more than ever.

Exercise. Exercise is another pillar of health and longevity. The same goes for our immunity. Observational and randomized data suggest that regular moderate aerobic activity lowers upper respiratory tract infection days by ~20–40%, whereas prolonged high-intensity training can transiently increase susceptibility (7). Target 150–300 min/week of moderate effort, and as my Garmin watch always reminds me – listen to your body and don’t push too far beyond your limits during the cold season.

Ventilation and humidity. While clinical trial data are limited on this one, many respiratory viruses transmit efficiently in stale, dry air. Therefore, you need to keep CO₂ low (aim for fresh air or HEPA filters) and indoor humidity ~40-60% to support mucosal defenses.

Nose and throat care

Consider your nose and throat as a virus manufacturing plant. Therefore, these two needed a dedicated paragraph in this Nexus edition. So what can be done to reduce this pathogen manufacturing process as much as possible in your nose and throat?

Water gargling (yes, just water).

A Japanese randomized trial found simple water gargling 3 times a day reduced upper respiratory tract infection incidence by ~36% vs control (8).

This is a really significant reduction. It requires a bit of an effort, but it is not that hard to do as it looks. If you do it in the morning and in the evening after you brushed your teeth and during this evening routine just do some additional longer gargling, you only need to add it mid-day, for example after you had lunch.

Nasal saline irrigation or drops. Trials suggest hypertonic saline may shorten symptom duration and reduce household transmission during upper respiratory tract infections.

Pediatric randomized clinical trial data show around 2-day shorter colds with simple saline drops (9).

Use isotonic or hypertonic saline once or twice daily when congested or after high-risk exposures. Important to note that antiseptic gargles (e.g., povidone-iodine) have in-vitro virucidal activity and small, setting-specific trials, but broad prevention data are limited. Plain water or saline have the best safety and clinical trials support everyday use.

Supplements and nutraceuticals: what do clinical trial data say?

Vitamin D

When vitamin D levels are low, your immune system loses a key form of support. Several randomized controlled trials and large meta-analyses found that people with low serum 25-hydroxyvitamin D (25[OH]D) had higher risk of acute respiratory infections (including those caused by common cold viruses); for example one RCT found an odds ratio of ~2.1 for respiratory illness when baseline 25[OH]D was <50 nmol/L (10). Other meta-analyses of ~45 000 participants showed that vitamin D supplementation modestly reduced the risk of such infections (e.g., OR ~0.91) when given daily rather than as large bolus doses.

Does it prevent infections? A widely cited 2017 IPD meta-analysis reported a modest protective effect against acute respiratory infections, especially with daily/weekly dosing and in people with low baseline levels. However, an updated 2021–2024 meta-analysis including newer large RCTs found no statistically significant preventive effect overall. Conclusion: correct deficiency for general health; don’t rely on vitamin D alone to prevent colds/flu (11).

Dosing/Safety. Typical intakes are 600–800 IU/day; do not exceed 4000 IU/day long-term without medical supervision.

Zinc (lozenges at first symptoms)

Many people still think that when they feel first symptoms of common cold, they should take high doses of Vitamin C. But instead, you should take zinc.

Treatment (not prevention). Meta-analyses of high-dose zinc acetate lozenges (≥75–80 mg elemental zinc/day divided) started within 24 h shorten cold duration meaningfully in adults; results vary by formulation and dose (12). Avoid citric/acidic additives that chelate zinc.

Safety. Limit total zinc <40 mg/day if used chronically. Short courses at higher doses for colds are common in trials but can cause nausea, metallic taste, and interfere with copper if overused. Avoid intranasal zinc (anosmia risk).

Vitamin C

Prevention. As mentioned, routine vitamin C does not prevent colds in the general population. It may halve incidence in people under brief, severe physical stress (e.g., marathoners) (13).

Treatment. Regular supplementation (≥200 mg/day) shortens duration and may reduce severity, though starting after onset is less reliable. 1 g/day is common during episodes, divide doses to limit GI upset (14).

Probiotics

Multiple randomized clinical trials and a 2022 Cochrane Review suggest probiotics may reduce the risk and number of URTI episodes and days ill in adults and children (strain-specific effects, certainty moderate) (15). Consider daily Lactobacillus/Bifidobacterium blends during the season. Including fermented products such as yogurt, kefir, sauerkraut (fermented cabbage), kimchi, or kombucha (without added sugar) in the diet may help maintain a healthy airway and gut microbiome, while targeted daily supplementation with these strains during the high-incidence season can provide an additional protective effect.

Bovine colostrum

Athletic and young-adult trials (doses from 20–60 g/day of concentrated colostrum protein) show fewer URTI episodes and favourable mucosal immune markers. A 2022 meta-analysis reports a significant reduction in URTI risk (16). It has to be noted that evidence is promising but heterogeneous. Choose tested products and consider dosing (practical regimens are often 5–20 g/day) given GI tolerance. I use it daily during the cold season, it does not have the best taste though so be prepared.

Quercetin and elderberry – low or no evidence

Quercetin. In community randomized clinical trials Quesrcitin did not reduce upper respiratory tract infection incidence overall (possible benefit in fitter middle-aged subgroups, small studies in athletes post-exertion) (17). Definitely not a first-line.

Elderberry (Sambucus nigra). Small randomized clinical trial/meta-analyses suggest shorter duration/less severe symptoms after onset, but prevention data are limited and overall certainty is low-to-moderate (18). Not a primary prevention.

Supplements safety reminders

A word supplement doesn’t by default mean safe whatever you do with it. Couple of important reminders:

Avoid mega-dosing;
Check interactions (e.g., zinc with certain antibiotics/diuretics);
Pregnant or immunocompromised individuals should review any supplement with a clinician.

Just a reminder – I have shared some insights about food supplements and what information to take into account while choosing the brand in one of my previous Nexus editions:

The Ugly Truth About Food Supplements

❌ Things people do for colds that don’t actually prevent or cure them

Going outside with wet hair doesn’t cause colds, viruses do.
“Sweating out” a cold in saunas or under heavy blankets has no proven benefit.
Drinking alcohol to “disinfect your throat” doesn’t help, and it may weaken immunity.
Using antibiotics for a viral cold is ineffective and causes resistance.
Essential oils in diffusers – no reliable evidence they prevent viral infections.
Megadosing vitamins “at the first sneeze” does not prevent the infection from happening.
Keeping windows closed all winter worsens indoor viral spread, not improves it.
Regular steam inhalation to “kill viruses” – viruses aren’t cleared this way.
Eating “immune-boosting superfoods” – healthy diet helps long term, but doesn’t block colds
Silver sprays / colloidal silver – useless for this purpose and unsafe.
Nasal sprays with antibiotics – don’t work for viral colds and can harm your microbiome.
Taking oregano oil or random herbal drops – claims > evidence.
Chasing “immune boosters” marketed on social media – usually no randomized clinical trial support.

There’s no silver bullet against common colds. Protection needs to be complex: Influenza/RSV/COVID-19 vaccination (if eligible), hand hygiene, room ventilation, adequate sleep, moderate exercise, and simple local measures like gargling and nasal saline offers the best odds. Hope you enjoyed the read. More on health, wellness and longevity coming soon, stay tuned!