Qualidade das evidências 4.63/5
Pontuação de revisão em oito dimensões segundo a grelha de qualidade . Cada dimensão pontuada de 1 a 5.
- D1 Ancoragem nas fontes
- 4/5
- D2 Autoridade das fontes
- 5/5
- D3 Aritmética
- 5/5
- D4 Incerteza
- 4/5
- D5 Âmbito
- 5/5
- D6 Prosa
- 5/5
- D7 Honestidade sobre a perceção
- 4/5
- D8 Completude das ressalvas
- 5/5
Como o risco varia
O valor principal é uma média de situações muito diferentes. Veja como a probabilidade varia por cenário ou contexto:
1 em 1 000 000
No cohort has measured a respiratory-infection rate attributable to this scenario. Without an underlying viral exposure, cold feet on tile do not produce a cold. Point estimate is a structural "effectively zero" placeholder, not a measured rate.
1 em 7,1 · 14%
Matches the Eccles 2005 arm: ~14% self-reported cold symptoms within 4–5 days after a 20-minute cold-foot immersion vs ~6% in controls. This is a symptom-conversion rate in an already-exposed population under a severe chilling protocol, not an infection rate from going sockless at home.
1 em 20 · 5,0%
Very rough. Order of magnitude derived from WHO cold-housing guidance and UK excess-winter-mortality attribution (~21.5% of ~20,000–50,000 annual excess winter deaths → cold homes, concentrated in over-65s). The dominant pathways are cardiovascular and respiratory, not viral infection. Included as the subgroup the folk warning might actually apply to, even though it is almost never the one a grandmother has in mind when telling a child to put on slippers.
1 em 2,0 · 50%
For someone with a cold-triggered vascular or cardiac condition, bare feet on cold tile reliably produces the trigger (Raynaud's episode, anginal chest pain) — but this is the underlying condition expressing itself, not a new illness. Included only to flag that "cold feet cause real symptoms" is true in this subgroup without rescuing the viral- infection folk model.
O comprimento e o tom da barra classificam estes cenários entre si, não em relação a outros riscos. As probabilidades exatas são mostradas ao lado de cada um.
A crença popular de que andar por uma casa aquecida sem chinelos, meias ou um suéter causa um resfriado é mecanicamente errada na forma como é geralmente expressa, e modestamente correta numa forma muito mais restrita do que as pessoas que a transmitem tendem a significar. Resfriados são causados por vírus (o CDC estima o número em mais de 200 vírus respiratórios distintos, sendo os rinovírus os mais comuns), e são transmitidos por gotículas e contato, não pela temperatura. Sem uma exposição viral subjacente, pés descalços no azulejo produzem pés frios e nada mais. A parte do modelo popular que sobrevive ao contato com a evidência é mais restrita: Johnson e Eccles (Cardiff, 2005) mostraram num ensaio randomizado com 180 pessoas que uma imersão de 20 minutos dos pés em água fria elevou os sintomas de resfriado autorrelatados nos 4–5 dias seguintes de 6% para 14%, e Foxman et al. (PNAS, 2015) mostraram que o rinovírus se replica melhor e a resposta inata de interferon é mais fraca na temperatura mais fria de 33–35 °C da cavidade nasal do que a 37 °C. Esses dois resultados juntos apoiam uma única afirmação específica: o resfriamento pode converter uma portagem viral subclínica num resfriado sintomático. Eles não apoiam a afirmação de que a exposição ao frio produz doença do nada.
O que é interessante sobre este medo em particular é a lacuna entre o cenário que ele nomeia e o cenário onde o frio em casa realmente mata pessoas. O aviso popular é geralmente dirigido a uma criança ou adulto saudável numa casa aquecida (coloque chinelos, não se sente em azulejos frios, não ande com cabelo molhado), onde o efeito de modulação de Eccles é o limite do que a evidência permite e nenhuma coorte tentou medir uma taxa de infecção por inverno atribuível a isso. O cenário onde o frio interno é inequivocamente letal é quase o oposto demográfico: idosos frágeis residentes em casas mantidas abaixo de 16–18 °C, onde as Diretrizes de Habitação e Saúde da OMS de 2018 e os dados de mortalidade excessiva no inverno do UK ONS identificam algo como 21.5% de 20,000–50,000 mortes anuais excessivas no inverno como atribuíveis a habitações frias, com doenças circulatórias e respiratórias como as causas dominantes. Esse dano é sobre a temperatura ambiente do quarto e o estresse vascular, não sobre esquecer as meias.
Onde o enquadramento “negligenciável” não se aplica: qualquer pessoa com fenômeno de Raynaud desencadeará de forma confiável um episódio a partir de azulejos frios, independentemente de infecção, e a angina induzida pelo frio é um evento cardíaco real para os suscetíveis. Leitores imunocomprometidos portadores de um vírus respiratório podem estar mais próximos do braço de 14% de Eccles do que da linha de base da população geral, embora o estudo não tivesse poder estatístico para afirmá-lo. O subgrupo específico para o qual o aviso popular precisaria ser direcionado para corresponder aos dados de mortalidade por frio em casa (idosos frágeis e bebês em habitações subaquecidas, especialmente com doença cardiorrespiratória existente) é geralmente não o subgrupo que realmente recebe o aviso. O conselho sobre chinelos é, na maioria das vezes, o instinto cultural certo apontado para a exposição errada.
Curiosidades relacionadas
Andar na chuva nao te dara um resfriado. Sentar em superficies frias nao causara infeccoes de bexiga. Estar pouco agasalhado nao te fara adoecer. Virus causam infeccoes. Temperatura nao.
Registro de evidências
Cada número abaixo é o que cada fonte relatou, com a citação literal em que nos baseamos e como chegamos ao nosso valor. Clique em qualquer link para verificar diretamente.
2/5 fontes verificadas de forma independente palavra por palavra em relação à fonte citada
-
[1] Family Practice (Oxford Academic), via PubMed — Acute cooling of the feet and the onset of common cold symptoms
Acute cooling of the feet and the onset of common cold symptomsSee all 3 Likelier entries citing this source →
- Estatística
13/90 chilled subjects vs 5/90 controls self-reported cold symptoms in the 4–5 days after a 20-minute cold-foot immersion (P=0.047)- Trecho
“"There is a common folklore that chilling of the body surface causes the development of common cold symptoms, but previous clinical research has failed to demonstrate any effect of cold exposure on susceptibility to infection with common cold viruses. [...] 13/90 subjects who were chilled reported they were suffering from a cold in the 4/5 days after the procedure compared to 5/90 control subjects (P=0.047). [...] Acute chilling of the feet causes the onset of common cold symptoms in around 10% of subjects who are chilled. Further studies are needed to determine the relationship of symptom generation to any respiratory infection." ”
- Dados da fonte de
- 2005-12-01
- Acessado
- 2026-04-16 · cópia arquivada
- Cálculo
- This is the canonical trial behind any "cold feet causes colds" claim. Critical qualifier the authors themselves flag: the study measured self-reported symptoms, not laboratory-confirmed new infections. The plausible mechanism the authors propose is that reflex vasoconstriction in the upper airway on cold- foot exposure reduces mucosal blood flow and temporarily lowers local defences — converting a pre-existing subclinical carriage of rhinovirus or another respiratory virus into a symptomatic cold. That is a modulation effect, not a causation effect. Without an underlying viral exposure, cooling the feet is not expected to produce illness from nothing. 90 subjects per arm gives an absolute difference of 8 percentage points (14% vs 6%); the confidence bound is wide, and no replication of comparable rigour exists at the scale needed to attach a per-winter probability to "no slippers at home."
- Independência
- Independent single-centre RCT at Cardiff (Common Cold Centre); editorially independent of the CDC and WHO sources. The Foxman 2015 mechanistic paper below provides a biological model compatible with Eccles' clinical result but was conducted in a separate lab with different methodology (mouse airway cells, not human subjects).
-
[2] Proceedings of the National Academy of Sciences (PNAS), via PubMed — Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells Verificado
Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cellsSee all 2 Likelier entries citing this source →
- Estatística
Rhinovirus replicates more robustly at 33–35 °C (nasal cavity) than at 37 °C (core body), with weaker interferon/antiviral response at the cooler temperature- Trecho
“"Most isolates of human rhinovirus, the common cold virus, replicate more robustly at the cool temperatures found in the nasal cavity (33–35 °C) than at core body temperature (37 °C). [...] These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature." ”
- Dados da fonte de
- 2015-01-20
- Acessado
- 2026-04-16 · cópia arquivada
- Verificação
- Trecho obtido novamente de forma independente e confirmado palavra por palavra em relação à fonte citada durante nossa auditoria de fundamentação.
- Cálculo
- Foxman et al. supplies the cleanest known mechanism for any cold-exposure- to-cold-illness signal: rhinovirus itself replicates better in a cooler nose, and the innate interferon response is weaker at 33 °C than at 37 °C. This makes Eccles' symptom-onset result biologically plausible without rescuing the folk model. The study is mouse airway cells in vitro, not an epidemiological measurement, and no study has translated the temperature- dependent replication curve into a per-exposure infection probability for a human wearing socks versus going barefoot. The mechanism is real; the epidemiological effect size at normal indoor conditions is not quantified.
- Independência
- Yale laboratory study with no authorship, funding, or institutional overlap with the Cardiff Eccles group; treat as methodologically independent mechanistic corroboration. Independent of the CDC and WHO sources.
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[3] US Centers for Disease Control and Prevention — About the Common Cold
About the Common ColdSee all 2 Likelier entries citing this source →
- Estatística
More than 200 respiratory viruses cause colds; rhinoviruses are the most frequent cause; primary spread is droplets and contact- Trecho
“"More than 200 respiratory viruses can cause colds. Rhinoviruses are the most frequent cause of colds in the United States. [...] Most respiratory viruses are spread through droplets that an infected person releases when they cough or sneeze. These droplets can enter your body if you breathe them in or touch a contaminated surface and then touch your eyes, nose, or mouth." ”
- Dados da fonte de
- 2026-02-19
- Acessado
- 2026-04-16 · cópia arquivada
- Cálculo
- CDC's current patient-facing page is the plain-language anchor for the "colds are viral, not thermal" frame. The folk model treats cold exposure as causative; CDC treats virus exposure as causative and does not list chilling or being under-dressed indoors as a transmission route at all. The Eccles and Foxman results sit downstream of this: you still need the virus. Without rhinovirus or one of the other ~200 candidates in your airway, cold feet on tile do not produce a cold.
- Independência
- Institutional CDC public-health guidance; editorially independent of the Eccles clinical trial and Foxman mechanistic paper, though it aligns with both.
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[4] World Health Organization (via NCBI Bookshelf) — Low indoor temperatures and insulation — WHO Housing and Health Guidelines Verificado
Low indoor temperatures and insulation — WHO Housing and Health Guidelines- Estatística
WHO recommends minimum indoor temperature of 18 °C to protect general populations; higher minimum for vulnerable groups (older people, children, chronic cardiorespiratory illness)- Trecho
“"For countries with temperate or colder climates, 18 °C has been proposed as a safe and well-balanced indoor temperature to protect the health of general populations during cold seasons. [...] A higher minimum indoor temperature than 18 °C may be necessary for vulnerable groups including older people, children and those with chronic illnesses, particularly cardiorespiratory disease." ”
- Dados da fonte de
- 2018-11-27
- Acessado
- 2026-04-16 · cópia arquivada
- Verificação
- Trecho obtido novamente de forma independente e confirmado palavra por palavra em relação à fonte citada durante nossa auditoria de fundamentação.
- Cálculo
- WHO's guideline is the authoritative carve-out for the one scenario in which "being under-dressed at home" really does kill people: under-heated housing in cold climates, especially for the elderly and those with cardiorespiratory disease. The exposure here is the ambient indoor temperature (below ~18 °C sustained), not a barefoot afternoon in a heated 21 °C living room. The outcome is cardiovascular and respiratory morbidity and mortality, not the common cold. This is the reason the headline framing ("folk belief overrated") must be paired with an explicit vulnerable-group caveat rather than a blanket dismissal.
- Independência
- WHO expert consensus guideline synthesising the cold-housing evidence base. Editorially independent of the Eccles, Foxman, and CDC sources and addresses a distinct exposure-outcome pair (sustained low ambient temperature → cardiovascular/respiratory death), not symptom onset of the common cold.
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[5] UK Parliamentary Office of Science and Technology — Winter mortality (POSTnote 752)
Winter mortality (POSTnote 752)- Estatística
Excess winter deaths in England and Wales ranged ~20,000–50,000/year 2000–2019; ~21.5% of excess winter deaths attributable to cold homes; most deaths from circulatory or respiratory disease among the elderly- Trecho
“"Between 2000 and 2019, excess winter deaths ranged from 20,000 to 50,000 a year [...] Most excess winter deaths are due to circulatory or respiratory diseases and the majority occur amongst the elderly population. [...] It has been estimated that 10% of excess winter deaths are attributable to fuel poverty and 21.5% to cold homes." ”
- Dados da fonte de
- 2024-01-01
- Acessado
- 2026-04-16 · cópia arquivada
- Cálculo
- This is the population-scale number for the one real cold-in-the-home harm: under-heated housing kills elderly people through cardiovascular and respiratory pathways, not through infection. It does not apply to the folk-belief scenario (healthy adult, barefoot in a warm house) and should not be aggregated with the Eccles symptom-onset figure. Used here only to bound the vulnerable-group subgroup in the regional breakdown and to keep the caveats honest about who the folk warning, repurposed, actually applies to.
- Independência
- UK Parliament research briefing drawing on ONS winter-mortality data and NICE fuel-poverty reviews. Editorially independent of the WHO guideline (though it references the same underlying epidemiology) and independent of the Eccles, Foxman, and CDC sources.